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Showing content from https://github.com/mythz/java-linq-examples below:

mythz/java-linq-examples: C#'s 101 LINQ Samples translated to Java

Port of the C# 101 LINQ Samples rewritten into Andriod-compatible Java 1.7.

Compare Java to other LINQ examples written in:

• Kotlin
• Groovy
• Swift
• Clojure
• Dart
• Elixir
• Python
• #Script code
• #Script lisp

If you're looking for an effortles typed API for consuming .NET Web Services in pure Java or Android Java Apps checkout ServiceStack's Java Add ServiceStack Reference.

Each of the LINQ Examples can be run from the included Android App with its results logged to the screen:

Run the included Android Studio project to execute all the examples. You can also choose to only run specific examples by commenting out any of the sections you're not interested in MainActivity.java.

A copy of the LINQ examples output is also available in linq-log.txt.

The samples below mirrors the C# LINQ samples layout with the names of the top-level Java methods matching their corresponding C# examples.

Unlike many modern languages supporting a functional-style, Java doesn't have any LINQ-like utils built-in by default. It's also not very extensible which combined with the lack of proper Type Inference, Type Erasure and Closures in Java 1.7 makes the equivalent Java source code particularly more verbose.

To improve the development experience in Java, we've added common functional utils to simplify programming in a functional style inside ServiceStack's Java and Android Client Library: net.servicestack:android.

To include it in your Android Studio project, add it to your build.gradle dependency, e.g:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'net.servicestack:android:1.0.24'
}

Pure Java projects should add the net.servicestack:client dependency instead:

dependencies {
    compile 'net.servicestack:client:1.0.24'
}

Alternatively this library is also automatically added when Adding a Typed Remote Service Reference with ServiceStack IDE Plugins for Intellij IDEA and Eclipse Maven projects.

Once the dependency is added you can add a static import to access all the functional utils used in the LINQ examples below:

import static net.servicestack.func.Func.*;

For a side-by-side comparison, the original C# source code is displayed above the equivalent Java translation.

• The Output shows the logging output of running the Java Android App.
• Outputs ending with ... illustrates only a partial response is displayed.
• The C# ObjectDumper util used is downloadable from MSDN - ObjectDumper.zip

The Java LINQ Examples are limited to Java 1.7 so they're available on Android.

//c#
public void Linq1() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var lowNums = 
        from n in numbers 
        where n < 5 
        select n; 
  
    Console.WriteLine("Numbers < 5:"); 
    foreach (var x in lowNums) 
    { 
        Console.WriteLine(x); 
    } 
}  

//java
public void linq1(){
    int[] numbers = new int[]{ 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> lowNums = filter(toList(numbers), new Predicate<Integer>() {
        @Override
        public boolean apply(Integer n) {
            return n < 5;
        }
    });

    Log.d("Numbers < 5:");
    for (int n : lowNums){
        Log.d(n);
    }
}

//c#
public void Linq2() 
{ 
    List<Product> products = GetProductList(); 
  
    var soldOutProducts = 
        from p in products 
        where p.UnitsInStock == 0 
        select p; 
  
    Console.WriteLine("Sold out products:"); 
    foreach (var product in soldOutProducts) 
    { 
        Console.WriteLine("{0} is sold out!", product.ProductName); 
    } 
} 

//java
public void linq2(){
    List<Product> products = getProductList();

    List<Product> soldOutProducts = filter(products, new Predicate<Product>() {
        @Override
        public boolean apply(Product p) {
            return p.unitsInStock == 0;
        }
    });

    Log.d("Sold out products:");
    for (Product p : soldOutProducts) {
        Log.d(p.productName + " is sold out!");
    }
}

Sold out products:
Chef Anton's Gumbo Mix is sold out!
Alice Mutton is sold out!
Thüringer Rostbratwurst is sold out!
Gorgonzola Telino is sold out!
Perth Pasties is sold out!

//c#
public void Linq3() 
{ 
    List<Product> products = GetProductList(); 
  
    var expensiveInStockProducts = 
        from p in products 
        where p.UnitsInStock > 0 && p.UnitPrice > 3.00M 
        select p; 
  
    Console.WriteLine("In-stock products that cost more than 3.00:"); 
    foreach (var product in expensiveInStockProducts) 
    { 
        Console.WriteLine("{0} is in stock and costs more than 3.00.", product.ProductName); 
    } 
} 

//java
public void linq3(){
    List<Product> products = getProductList();

    ArrayList<Product> expensiveInStockProducts = filter(products, new Predicate<Product>() {
        @Override
        public boolean apply(Product p) {
            return p.unitsInStock > 0 && p.unitPrice > 3.00;
        }
    });

    Log.d("In-stock products that cost more than 3.00:");
    for (Product p : expensiveInStockProducts) {
        Log.d(p.productName + " is in stock and costs more than 3.00.");
    }
}

In-stock products that cost more than 3.00:
Chai is in stock and costs more than 3.00.
Chang is in stock and costs more than 3.00.
Aniseed Syrup is in stock and costs more than 3.00.
...

//c#
public void Linq4() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var waCustomers = 
        from c in customers 
        where c.Region == "WA" 
        select c; 
  
    Console.WriteLine("Customers from Washington and their orders:"); 
    foreach (var customer in waCustomers) 
    { 
        Console.WriteLine("Customer {0}: {1}", customer.CustomerID, customer.CompanyName); 
        foreach (var order in customer.Orders) 
        { 
            Console.WriteLine("  Order {0}: {1}", order.OrderID, order.OrderDate); 
        } 
    } 
} 

//java
public void linq4(){
    List<Customer> customers = getCustomerList();

    List<Customer> waCustomers = filter(customers, new Predicate<Customer>() {
        @Override
        public boolean apply(Customer c) {
            return "WA".equals(c.region);
        }
    });

    Log.d("Customers from Washington and their orders:");
    for (Customer c : waCustomers){
        Log.d("Customer " + c.customerId + " " + c.companyName);
        for (Order o : c.orders){
            Log.d("  Order " + o.orderId + ": " + dateFmt(o.orderDate));
        }
    }
}

Customers from Washington and their orders:
Customer LAZYK Lazy K Kountry Store
  Order 10482: 1997/03/21
  Order 10545: 1997/05/22
Customer TRAIH Trail's Head Gourmet Provisioners
  Order 10574: 1997/06/19
  Order 10577: 1997/06/23
  Order 10822: 1998/01/08
  ...

//c#
public void Linq5() 
{ 
    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var shortDigits = digits.Where((digit, index) => digit.Length < index); 
  
    Console.WriteLine("Short digits:"); 
    foreach (var d in shortDigits) 
    { 
        Console.WriteLine("The word {0} is shorter than its value.", d); 
    } 
}

//java
public void linq5(){
    String[] digits = new String[]{ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<String> shortDigits = filteri(digits, new PredicateIndex<String>() {
        @Override
        public boolean apply(String s, int i) {
            return s.length() < i;
        }
    });

    Log.d("Short digits:");
    for (String d : shortDigits){
        Log.d("The word " + d + " is shorter than its value.");
    }
}

Short digits:
The word five is shorter than its value.
The word six is shorter than its value.
The word seven is shorter than its value.
The word eight is shorter than its value.
The word nine is shorter than its value.

//c#
public void Linq6() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var numsPlusOne = 
        from n in numbers 
        select n + 1; 
  
    Console.WriteLine("Numbers + 1:"); 
    foreach (var i in numsPlusOne) 
    { 
        Console.WriteLine(i); 
    } 
}

//java
public void linq06(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> numsPlusOne = map(toList(numbers), new Function<Integer, Integer>() {
        @Override
        public Integer apply(Integer i) {
            return i + 1;
        }
    });

    Log.d("Numbers + 1:");
    for (Integer n : numsPlusOne){
        Log.d(n);
    }
}

Numbers + 1:
6
5
2
4
10
9
7
8
3
1

//c#
public void Linq7() 
{ 
    List<Product> products = GetProductList(); 
  
    var productNames = 
        from p in products 
        select p.ProductName; 
  
    Console.WriteLine("Product Names:"); 
    foreach (var productName in productNames) 
    { 
        Console.WriteLine(productName); 
    } 
}

//java
public void linq07(){
    List<Product> products = getProductList();

    List<String> productNames = map(products, new Function<Product, String>() {
        @Override
        public String apply(Product p) {
            return p.productName;
        }
    });

    Log.d("Product Names:");
    for (String productName : productNames){
        Log.d(productName);
    }
}

Product Names:
Chai
Chang
Aniseed Syrup
Chef Anton's Cajun Seasoning
Chef Anton's Gumbo Mix
...

//c#
public void Linq8() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
    string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var textNums = 
        from n in numbers 
        select strings[n]; 
  
    Console.WriteLine("Number strings:"); 
    foreach (var s in textNums) 
    { 
        Console.WriteLine(s); 
    } 
}

//java
public void linq08(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
    final String[] strings = new String[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<String> textNums = map(toList(numbers), new Function<Integer, String>() {
        @Override
        public String apply(Integer n) {
            return strings[n];
        }
    });

    Log.d("Number strings:");
    for (String s : textNums){
        Log.d(s);
    }
}

Number strings:
five
four
one
three
nine
eight
six
seven
two
zero

//c#
public void Linq9() 
{ 
    string[] words = { "aPPLE", "BlUeBeRrY", "cHeRry" }; 
  
    var upperLowerWords = 
        from w in words 
        select new { Upper = w.ToUpper(), Lower = w.ToLower() }; 
  
    foreach (var ul in upperLowerWords) 
    { 
        Console.WriteLine("Uppercase: {0}, Lowercase: {1}", ul.Upper, ul.Lower); 
    } 
}

//java
public void linq09(){
    String[] words = new String[]{ "aPPLE", "BlUeBeRrY", "cHeRry" };

    List<Tuple<String,String>> upperLowerWords = map(words, new Function<String, Tuple<String,String>>(){
        @Override
        public Tuple<String,String> apply(String w) {
            return new Tuple<>(w.toUpperCase(), w.toLowerCase());
        }
    });

    for (Tuple<String,String> ul : upperLowerWords){
        Log.d("Uppercase: " + ul.A + ", Lowercase: " + ul.B);
    }
}

Uppercase: APPLE, Lowercase: apple
Uppercase: BLUEBERRY, Lowercase: blueberry
Uppercase: CHERRY, Lowercase: cherry

//c#
public void Linq10() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
    string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var digitOddEvens = 
        from n in numbers 
        select new { Digit = strings[n], Even = (n % 2 == 0) }; 
  
    foreach (var d in digitOddEvens) 
    { 
        Console.WriteLine("The digit {0} is {1}.", d.Digit, d.Even ? "even" : "odd"); 
    } 
}

//java
public void linq10(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
    final String[] strings = new String[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<Tuple<String, Boolean>> digitOddEvens = map(toList(numbers), new Function<Integer, Tuple<String, Boolean>>() {
        @Override
        public Tuple<String, Boolean> apply(Integer n) {
            return new Tuple<>(strings[n], n % 2 == 0);
        }
    });

    for (Tuple<String,Boolean> d : digitOddEvens){
        Log.d("The digit " + d.A + " is " + (d.B ? "even" : "odd") + ".");
    }
}

The digit five is odd.
The digit four is even.
The digit one is odd.
The digit three is odd.
The digit nine is odd.
The digit eight is even.
The digit six is even.
The digit seven is odd.
The digit two is even.
The digit zero is even.

//c#
public void Linq11() 
{ 
    List<Product> products = GetProductList(); 
  
    var productInfos = 
        from p in products 
        select new { p.ProductName, p.Category, Price = p.UnitPrice }; 
  
    Console.WriteLine("Product Info:"); 
    foreach (var productInfo in productInfos) 
    { 
        Console.WriteLine("{0} is in the category {1} and costs {2} per unit.", productInfo.ProductName, productInfo.Category, productInfo.Price); 
    } 
}

//java
public void linq11(){
    List<Product> products = getProductList();

    List<Tuple3<String,String,Double>> productInfos = map(products, new Function<Product, Tuple3<String, String, Double>>() {
        @Override
        public Tuple3<String, String, Double> apply(Product p) {
            return new Tuple3<>(p.productName, p.category, p.unitPrice);
        }
    });

    Log.d("Product Info:");
    for (Tuple3<String,String,Double> productInfo : productInfos){
        Log.d(productInfo.A + " is in the category " + productInfo.B + " and costs " + productInfo.C + " per unit.");
    }
}

Product Info:
Chai is in the category Beverages and costs 18.0 per unit.
Chang is in the category Beverages and costs 19.0 per unit.
Aniseed Syrup is in the category Condiments and costs 10.0 per unit.
...

//c#
public void Linq12() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var numsInPlace = numbers.Select((num, index) => new { Num = num, InPlace = (num == index) }); 
  
    Console.WriteLine("Number: In-place?"); 
    foreach (var n in numsInPlace) 
    { 
        Console.WriteLine("{0}: {1}", n.Num, n.InPlace); 
    } 
}

//java
public void linq12(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Tuple<Integer,Boolean>> numsInPlace = mapi(toList(numbers), new FunctionIndex<Integer, Tuple<Integer, Boolean>>() {
        @Override
        public Tuple<Integer, Boolean> apply(Integer num, int index) {
            return new Tuple<>(num, num == index);
        }
    });

    Log.d("Number: In-place?");
    for (Tuple<Integer,Boolean> n : numsInPlace){
        Log.d(n.A + ": " + n.B);
    }
}

Number: In-place?
5: false
4: false
1: false
3: true
9: false
8: false
6: true
7: true
2: false
0: false

//c#
public void Linq13() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var lowNums = 
        from n in numbers 
        where n < 5 
        select digits[n]; 
  
    Console.WriteLine("Numbers < 5:"); 
    foreach (var num in lowNums) 
    { 
        Console.WriteLine(num); 
    } 
}

//java
public void linq13(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
    final String[] digits = new String[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<String> lowNums = map(
        filter(toList(numbers), new Predicate<Integer>() {
            @Override
            public boolean apply(Integer n) {
                return n < 5;
            }
        }),
        new Function<Integer, String>() {
            @Override
            public String apply(Integer n){
                return digits[n];
            }
        });

    Log.d("Numbers < 5:");
    for (String num : lowNums){
        Log.d(num);
    }
}

Numbers < 5:
four
one
three
two
zero

//c#
public void Linq14() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 
  
    var pairs = 
        from a in numbersA 
        from b in numbersB 
        where a < b 
        select new { a, b }; 
  
    Console.WriteLine("Pairs where a < b:"); 
    foreach (var pair in pairs) 
    { 
        Console.WriteLine("{0} is less than {1}", pair.a, pair.b); 
    } 
}

//java
public void linq14(){
    int[] numbersA = new int[] { 0, 2, 4, 5, 6, 8, 9 };
    final int[] numbersB = new int[] { 1, 3, 5, 7, 8 };

    List<Tuple<Integer,Integer>> pairs = expand(
        map(toList(numbersA), new Function<Integer,List<Tuple<Integer,Integer>>>() {
            @Override
            public List<Tuple<Integer,Integer>> apply(final Integer a) {
                return map(filter(toList(numbersB), new Predicate<Integer>() {
                    @Override
                    public boolean apply(Integer b) {
                        return a < b;
                    }
                }), new Function<Integer, Tuple<Integer,Integer>>() {
                    @Override
                    public Tuple<Integer, Integer> apply(Integer b) {
                        return new Tuple<>(a,b);
                    }
                });
            }
        })
    );

    Log.d("Pairs where a < b:");
    for (Tuple<Integer,Integer> pair : pairs){
        Log.d(pair.A + " is less than " + pair.B);
    }
}

Pairs where a < b:
0 is less than 1
0 is less than 3
0 is less than 5
0 is less than 7
0 is less than 8
2 is less than 3
2 is less than 5
2 is less than 7
2 is less than 8
4 is less than 5
4 is less than 7
4 is less than 8
5 is less than 7
5 is less than 8
6 is less than 7
6 is less than 8

//c#
public void Linq15() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var orders = 
        from c in customers 
        from o in c.Orders 
        where o.Total < 500.00M 
        select new { c.CustomerID, o.OrderID, o.Total }; 
  
    ObjectDumper.Write(orders); 
}

//java
public void linq15(){
    List<Customer> customers = getCustomerList();

    List<Tuple3<String, Integer, Double>> orders = expand(
        map(customers, new Function<Customer, List<Tuple3<String, Integer, Double>>>() {
            @Override
            public List<Tuple3<String, Integer, Double>> apply(final Customer c) {
                return map(filter(c.orders, new Predicate<Order>() {
                    @Override
                    public boolean apply(Order o) {
                        return o.total < 500;
                    }
                }), new Function<Order, Tuple3<String, Integer, Double>>() {
                    @Override
                    public Tuple3<String, Integer, Double> apply(Order o) {
                        return new Tuple3<>(c.customerId, o.orderId, o.total);
                    }
                });
            }
        })
    );

    for (Tuple3<?,?,?> o : orders){
        Log.d(o);
    }
}

(ALFKI, 10702, 330.0)
(ALFKI, 10952, 471.2)
(ANATR, 10308, 88.8)
(ANATR, 10625, 479.75)
...

//c#
public void Linq16() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var orders = 
        from c in customers 
        from o in c.Orders 
        where o.OrderDate >= new DateTime(1998, 1, 1) 
        select new { c.CustomerID, o.OrderID, o.OrderDate }; 
  
    ObjectDumper.Write(orders); 
}

//java
public void linq16(){
    List<Customer> customers = getCustomerList();

    final Date date = new Date(98, 0, 1); //= 1998-01-01

    List<Tuple3<String, Integer, Date>> orders = expand(
        map(customers, new Function<Customer, List<Tuple3<String, Integer, Date>>>() {
            @Override
            public List<Tuple3<String, Integer, Date>> apply(final Customer c) {
                return map(filter(c.orders, new Predicate<Order>() {
                    @Override
                    public boolean apply(Order o) {
                        return o.orderDate.after(date);
                    }
                }), new Function<Order, Tuple3<String, Integer, Date>>() {
                    @Override
                    public Tuple3<String, Integer, Date> apply(Order o) {
                        return new Tuple3<>(c.customerId, o.orderId, o.orderDate);
                    }
                });
            }
        })
    );

    for (Tuple3<?,?,?> o : orders){
        Log.d(o);
    }
}

(ALFKI, 10835, Thu Jan 15 00:00:00 GMT+08:00 1998)
(ALFKI, 10952, Mon Mar 16 00:00:00 GMT+08:00 1998)
(ALFKI, 11011, Thu Apr 09 00:00:00 GMT+08:00 1998)
(ANATR, 10926, Wed Mar 04 00:00:00 GMT+08:00 1998)
(ANTON, 10856, Wed Jan 28 00:00:00 GMT+08:00 1998)
...

//c#
public void Linq17() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var orders = 
        from c in customers 
        from o in c.Orders 
        where o.Total >= 2000.0M 
        select new { c.CustomerID, o.OrderID, o.Total }; 
  
    ObjectDumper.Write(orders); 
}

//java
public void linq17(){
    List<Customer> customers = getCustomerList();

    List<Tuple3<String, Integer, Double>> orders = expand(
            map(customers, new Function<Customer, List<Tuple3<String, Integer, Double>>>() {
                @Override
                public List<Tuple3<String, Integer, Double>> apply(final Customer c) {
                    return map(filter(c.orders, new Predicate<Order>() {
                        @Override
                        public boolean apply(Order o) {
                            return o.total >= 2000;
                        }
                    }), new Function<Order, Tuple3<String, Integer, Double>>() {
                        @Override
                        public Tuple3<String, Integer, Double> apply(Order o) {
                            return new Tuple3<>(c.customerId, o.orderId, o.total);
                        }
                    });
                }
            })
    );

    for (Tuple3<?,?,?> o : orders){
        Log.d(o);
    }
}

(ANTON, 10573, 2082.0)
(AROUT, 10558, 2142.9)
(AROUT, 10953, 4441.25)
(BERGS, 10384, 2222.4)
(BERGS, 10524, 3192.65)
...

//c#
public void Linq18() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    DateTime cutoffDate = new DateTime(1997, 1, 1); 
  
    var orders = 
        from c in customers 
        where c.Region == "WA" 
        from o in c.Orders 
        where o.OrderDate >= cutoffDate 
        select new { c.CustomerID, o.OrderID }; 
  
    ObjectDumper.Write(orders); 
}

//java
public void linq18(){
    List<Customer> customers = getCustomerList();

    final Date cutoffDate = new Date(97,0,1); //1997-01-01

    List<Tuple<String, Integer>> orders = expand(
        map(
            filter(customers, new Predicate<Customer>() {
                @Override
                public boolean apply(Customer c) {
                    return "WA".equals(c.region);
                }
            })
            , new Function<Customer, List<Tuple<String, Integer>>>() {
            @Override
            public List<Tuple<String, Integer>> apply(final Customer c) {
                return map(filter(c.orders, new Predicate<Order>() {
                    @Override
                    public boolean apply(Order o) {
                        return o.orderDate.after(cutoffDate);
                    }
                }), new Function<Order, Tuple<String, Integer>>() {
                    @Override
                    public Tuple<String, Integer> apply(Order o) {
                        return new Tuple<>(c.customerId, o.orderId);
                    }
                });
            }
        })
    );

    for (Tuple<?,?> o : orders){
        Log.d(o);
    }
}

(LAZYK, 10482)
(LAZYK, 10545)
(TRAIH, 10574)
(TRAIH, 10577)
(TRAIH, 10822)
(WHITC, 10469)
(WHITC, 10483)
(WHITC, 10504)
(WHITC, 10596)
(WHITC, 10693)
(WHITC, 10696)
(WHITC, 10723)
(WHITC, 10740)
(WHITC, 10861)
(WHITC, 10904)
(WHITC, 11032)
(WHITC, 11066)

//c#
public void Linq19() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var customerOrders = 
        customers.SelectMany( 
            (cust, custIndex) => 
            cust.Orders.Select(o => "Customer #" + (custIndex + 1) + 
                                    " has an order with OrderID " + o.OrderID)); 
  
    ObjectDumper.Write(customerOrders); 
}

//java
public void linq19(){
    List<Customer> customers = getCustomerList();

    List<String> customerOrders = expand(
      mapi(customers, new FunctionIndex<Customer, List<String>>() {
          @Override
          public List<String> apply(Customer cust, final int custIndex) {
              return map(cust.orders, new Function<Order, String>() {
                  @Override
                  public String apply(Order o) {
                      return "Customer #" + (custIndex + 1) + " has an order with OrderID " + o.orderId;
                  }
              });
          }
      })
    );

    for (String x : customerOrders){
        Log.d(x);
    }
}

Customer #1 has an order with OrderID 10643
Customer #1 has an order with OrderID 10692
Customer #1 has an order with OrderID 10702
Customer #1 has an order with OrderID 10835
Customer #1 has an order with OrderID 10952
Customer #1 has an order with OrderID 11011
Customer #2 has an order with OrderID 10308
Customer #2 has an order with OrderID 10625
Customer #2 has an order with OrderID 10759
Customer #2 has an order with OrderID 10926
...

//c#
public void Linq20() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 

    var first3Numbers = numbers.Take(3); 
  
    Console.WriteLine("First 3 numbers:"); 
  
    foreach (var n in first3Numbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq20() {
    int[] numbers = new int[]{5, 4, 1, 3, 9, 8, 6, 7, 2, 0};

    List<Integer> first3Numbers = take(toList(numbers), 3);

    Log.d("First 3 numbers:");
    for (Integer n : first3Numbers) {
        Log.d(n);
    }
}

//c#
public void Linq21()   
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var first3WAOrders = ( 
        from c in customers 
        from o in c.Orders 
        where c.Region == "WA" 
        select new { c.CustomerID, o.OrderID, o.OrderDate }) 
        .Take(3); 
  
    Console.WriteLine("First 3 orders in WA:"); 
    foreach (var order in first3WAOrders) 
    { 
        ObjectDumper.Write(order); 
    } 
}

//java
public void linq21() {
    List<Customer> customers = getCustomerList();

    List<Tuple3<String, Integer, Date>> first3WAOrders =
        take(
            expand(
                map(filter(customers, new Predicate<Customer>() {
                    @Override
                    public boolean apply(Customer c) {
                        return "WA".equals(c.region);
                    }
                }),
                new Function<Customer, List<Tuple3<String, Integer, Date>>>() {
                    @Override
                    public List<Tuple3<String, Integer, Date>> apply(final Customer c) {
                        return map(c.orders, new Function<Order, Tuple3<String, Integer, Date>>() {
                            @Override
                            public Tuple3<String, Integer, Date> apply(Order o) {
                                return new Tuple3<>(c.customerId, o.orderId, o.orderDate);
                            }
                        });
                    }
                })
            ),
        3);

    Log.d("First 3 orders in WA:");
    for (Tuple3<?, ?, ?> o : first3WAOrders) {
        Log.d(o);
    }
}

First 3 orders in WA:
(LAZYK, 10482, Fri Mar 21 00:00:00 GMT+08:00 1997)
(LAZYK, 10545, Thu May 22 00:00:00 GMT+08:00 1997)
(TRAIH, 10574, Thu Jun 19 00:00:00 GMT+08:00 1997)

//c#
public void Linq22() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var allButFirst4Numbers = numbers.Skip(4); 
  
    Console.WriteLine("All but first 4 numbers:"); 
    foreach (var n in allButFirst4Numbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq22() {
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> allButFirst4Numbers = skip(toList(numbers), 4);

    Log.d("All but first 4 numbers:");
    for (Integer n : allButFirst4Numbers){
        Log.d(n);
    }
}

All but first 4 numbers:
9
8
6
7
2
0

//c#
public void Linq23()   
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var waOrders = 
        from c in customers 
        from o in c.Orders 
        where c.Region == "WA" 
        select new { c.CustomerID, o.OrderID, o.OrderDate }; 
  
    var allButFirst2Orders = waOrders.Skip(2); 
  
    Console.WriteLine("All but first 2 orders in WA:"); 
    foreach (var order in allButFirst2Orders) 
    { 
        ObjectDumper.Write(order); 
    } 
}

//java
public void linq23() {
    List<Customer> customers = getCustomerList();

    List<Tuple3<String, Integer, Date>> allButFirst2Orders =
        skip(
            expand(
                map(filter(customers, new Predicate<Customer>() {
                        @Override
                        public boolean apply(Customer c) {
                            return "WA".equals(c.region);
                        }
                    }),
                    new Function<Customer, List<Tuple3<String, Integer, Date>>>() {
                        @Override
                        public List<Tuple3<String, Integer, Date>> apply(final Customer c) {
                            return map(c.orders, new Function<Order, Tuple3<String, Integer, Date>>() {
                                @Override
                                public Tuple3<String, Integer, Date> apply(Order o) {
                                    return new Tuple3<>(c.customerId, o.orderId, o.orderDate);
                                }
                            });
                        }
                    })
                ),
            2);

    Log.d("All but first 2 orders in WA:");
    for (Tuple3<?, ?, ?> o : allButFirst2Orders) {
        Log.d(o);
    }
}

All but first 2 orders in WA:
(TRAIH, 10574, Thu Jun 19 00:00:00 GMT+08:00 1997)
(TRAIH, 10577, Mon Jun 23 00:00:00 GMT+08:00 1997)
(TRAIH, 10822, Thu Jan 08 00:00:00 GMT+08:00 1998)
(WHITC, 10269, Wed Jul 31 00:00:00 GMT+08:00 1996)
(WHITC, 10344, Fri Nov 01 00:00:00 GMT+08:00 1996)
(WHITC, 10469, Mon Mar 10 00:00:00 GMT+08:00 1997)
(WHITC, 10483, Mon Mar 24 00:00:00 GMT+08:00 1997)
(WHITC, 10504, Fri Apr 11 00:00:00 GMT+08:00 1997)
(WHITC, 10596, Fri Jul 11 00:00:00 GMT+08:00 1997)
(WHITC, 10693, Mon Oct 06 00:00:00 GMT+08:00 1997)
(WHITC, 10696, Wed Oct 08 00:00:00 GMT+08:00 1997)
(WHITC, 10723, Thu Oct 30 00:00:00 GMT+08:00 1997)
(WHITC, 10740, Thu Nov 13 00:00:00 GMT+08:00 1997)
(WHITC, 10861, Fri Jan 30 00:00:00 GMT+08:00 1998)
(WHITC, 10904, Tue Feb 24 00:00:00 GMT+08:00 1998)
(WHITC, 11032, Fri Apr 17 00:00:00 GMT+08:00 1998)
(WHITC, 11066, Fri May 01 00:00:00 GMT+08:00 1998)

//c#
public void Linq24() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 6); 
  
    Console.WriteLine("First numbers less than 6:"); 
    foreach (var n in firstNumbersLessThan6) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq24() {
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> firstNumbersLessThan6 = takeWhile(toList(numbers), new Predicate<Integer>() {
        @Override
        public boolean apply(Integer n) {
            return n < 6;
        }
    });

    Log.d("First numbers less than 6:");
    for (Integer n : firstNumbersLessThan6){
        Log.d(n);
    }
}

First numbers less than 6:
5
4
1
3

//c#
public void Linq25() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var firstSmallNumbers = numbers.TakeWhile((n, index) => n >= index); 
  
    Console.WriteLine("First numbers not less than their position:"); 
    foreach (var n in firstSmallNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq25() {
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> firstSmallNumbers = takeWhilei(toList(numbers), new PredicateIndex<Integer>() {
        @Override
        public boolean apply(Integer n, int index) {
            return n >= index;
        }
    });

    Log.d("First numbers not less than their position:");
    for (Integer n : firstSmallNumbers){
        Log.d(n);
    }
}

First numbers not less than their position:
5
4

//c#
public void Linq26() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var allButFirst3Numbers = numbers.SkipWhile(n => n % 3 != 0); 
  
    Console.WriteLine("All elements starting from first element divisible by 3:"); 
    foreach (var n in allButFirst3Numbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq26() {
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> allButFirst3Numbers = skipWhile(toList(numbers), new Predicate<Integer>() {
        @Override
        public boolean apply(Integer n) {
            return n % 3 != 0;
        }
    });

    Log.d("All elements starting from first element divisible by 3:");
    for (Integer n : allButFirst3Numbers){
        Log.d(n);
    }
}

All elements starting from first element divisible by 3:
3
9
8
6
7
2
0

//c#
public void Linq27() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var laterNumbers = numbers.SkipWhile((n, index) => n >= index); 
  
    Console.WriteLine("All elements starting from first element less than its position:"); 
    foreach (var n in laterNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq27() {
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Integer> laterNumbers = skipWhilei(toList(numbers), new PredicateIndex<Integer>() {
        @Override
        public boolean apply(Integer n, int index) {
            return n >= index;
        }
    });

    Log.d("All elements starting from first element less than its position:");
    for (Integer n : laterNumbers){
        Log.d(n);
    }
}

All elements starting from first element less than its position:
1
3
9
8
6
7
2
0

//c#
public void Linq28() 
{ 
    string[] words = { "cherry", "apple", "blueberry" }; 
  
    var sortedWords = 
        from w in words 
        orderby w 
        select w; 
  
    Console.WriteLine("The sorted list of words:"); 
    foreach (var w in sortedWords) 
    { 
        Console.WriteLine(w); 
    } 
}

//java
public void linq28(){
    String[] words = new String[] { "cherry", "apple", "blueberry" };

    List<String> sortedWords = orderBy(words);

    Log.d("The sorted list of words:");
    for (String w : sortedWords){
        Log.d(w);
    }
}

The sorted list of words:
apple
blueberry
cherry

//c#
public void Linq29() 
{ 
    string[] words = { "cherry", "apple", "blueberry" }; 
  
    var sortedWords = 
        from w in words 
        orderby w.Length 
        select w; 
  
    Console.WriteLine("The sorted list of words (by length):"); 
    foreach (var w in sortedWords) 
    { 
        Console.WriteLine(w); 
    } 
}

//java
public void linq29(){
    String[] words = new String[] { "cherry", "apple", "blueberry" };

    List<String> sortedWords = orderBy(words, new Function<String, Comparable>() {
        @Override
        public Comparable apply(String s) {
            return s.length();
        }
    });

    Log.d("The sorted list of words (by length):");
    for (String w : sortedWords){
        Log.d(w);
    }
}

The sorted list of words (by length):
apple
cherry
blueberry

//c#
public void Linq30() 
{ 
    List<Product> products = GetProductList(); 
  
    var sortedProducts = 
        from p in products 
        orderby p.ProductName 
        select p; 
  
    ObjectDumper.Write(sortedProducts); 
}

//java
public void linq30(){
    List<Product> products = getProductList();

    List<Product> sortedProducts = orderBy(products, new Function<Product, Comparable>() {
        @Override
        public Comparable apply(Product p) {
            return p.productName;
        }
    });

    for (Product p : sortedProducts){
        Log.d(p);
    }
}

(Product id=17, name=Alice Mutton, cat=Meat/Poultry, price=39.0, inStock=0)
(Product id=3, name=Aniseed Syrup, cat=Condiments, price=10.0, inStock=13)
(Product id=40, name=Boston Crab Meat, cat=Seafood, price=18.4, inStock=123)
(Product id=60, name=Camembert Pierrot, cat=Dairy Products, price=34.0, inStock=19)
(Product id=18, name=Carnarvon Tigers, cat=Seafood, price=62.5, inStock=42)
...

//c#
public void Linq31() 
{ 
    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" }; 
  
    var sortedWords = words.OrderBy(a => a, new CaseInsensitiveComparer()); 
  
    ObjectDumper.Write(sortedWords); 
} 

//java
public void linq31(){
    String[] words = new String[] { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

    List<String> sortedWords = orderBy(words, String.CASE_INSENSITIVE_ORDER);

    for (String w : sortedWords){
        Log.d(w);
    }
}

AbAcUs
aPPLE
BlUeBeRrY
bRaNcH
cHeRry
ClOvEr

//c#
public void Linq32() 
{ 
    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 }; 
  
    var sortedDoubles = 
        from d in doubles 
        orderby d descending 
        select d; 
  
    Console.WriteLine("The doubles from highest to lowest:"); 
    foreach (var d in sortedDoubles) 
    { 
        Console.WriteLine(d); 
    } 
}

//java
public void linq32(){
    double[] doubles = new double[] { 1.7, 2.3, 1.9, 4.1, 2.9 };

    List<Double> sortedDoubles = orderByDesc(toList(doubles));

    Log.d("The doubles from highest to lowest:");
    for (Double d : sortedDoubles){
        Log.d(d);
    }
}

The doubles from highest to lowest:
4.1
2.9
2.3
1.9
1.7

//c#
public void Linq33() 
{ 
    List<Product> products = GetProductList(); 
  
    var sortedProducts = 
        from p in products 
        orderby p.UnitsInStock descending 
        select p; 
  
    ObjectDumper.Write(sortedProducts); 
}

//java
public void linq33(){
    List<Product> products = getProductList();

    List<Product> sortedProducts = orderByDesc(products, new Function<Product, Integer>(){
        @Override
        public Integer apply(Product p) {
            return p.unitsInStock;
        }
    });

    for (Product p : sortedProducts){
        Log.d(p);
    }
}

(Product id=75, name=Rhönbräu Klosterbier, cat=Beverages, price=7.75, inStock=125)
(Product id=40, name=Boston Crab Meat, cat=Seafood, price=18.4, inStock=123)
(Product id=6, name=Grandma's Boysenberry Spread, cat=Condiments, price=25.0, inStock=120)
(Product id=55, name=Pâté chinois, cat=Meat/Poultry, price=24.0, inStock=115)
(Product id=61, name=Sirop d'érable, cat=Condiments, price=28.5, inStock=113)
...

//c#
public void Linq34() 
{ 
    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" }; 
  
    var sortedWords = words.OrderByDescending(a => a, new CaseInsensitiveComparer()); 
  
    ObjectDumper.Write(sortedWords); 
} 

//java
public void linq34(){
    String[] words = new String[] { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

    List<String> sortedWords = orderByDesc(words, String.CASE_INSENSITIVE_ORDER);

    for (String w : sortedWords){
        Log.d(w);
    }
}

ClOvEr
cHeRry
bRaNcH
BlUeBeRrY
aPPLE
AbAcUs

//c#
public void Linq35() 
{ 
    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var sortedDigits = 
        from d in digits 
        orderby d.Length, d 
        select d; 
  
    Console.WriteLine("Sorted digits:"); 
    foreach (var d in sortedDigits) 
    { 
        Console.WriteLine(d); 
    } 
}

//java
public void linq35(){
    String[] digits = new String[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<String> sortedDigits = orderBy(orderBy(digits), new Function<String, Comparable>() {
        @Override
        public Comparable apply(String s) {
            return s.length();
        }
    });

    Log.d("Sorted digits:");
    for (String d : sortedDigits){
        Log.d(d);
    }
}

Sorted digits:
one
six
two
five
four
nine
zero
eight
seven
three

//c#
public void Linq36() 
{ 
    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" }; 
  
    var sortedWords = 
        words.OrderBy(a => a.Length) 
             .ThenBy(a => a, new CaseInsensitiveComparer()); 
  
    ObjectDumper.Write(sortedWords); 
} 

//java
public void linq36(){
    String[] words = new String[] { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

    List<String> sortedWords = orderBy(orderBy(words, String.CASE_INSENSITIVE_ORDER), new Function<String, Comparable>() {
        @Override
        public Comparable apply(String s) {
            return s.length();
        }
    });

    for (String w : sortedWords){
        Log.d(w);
    }
}

aPPLE
AbAcUs
bRaNcH
cHeRry
ClOvEr
BlUeBeRrY

//c#
public void Linq37() 
{ 
    List<Product> products = GetProductList(); 
  
    var sortedProducts = 
        from p in products 
        orderby p.Category, p.UnitPrice descending 
        select p; 
  
    ObjectDumper.Write(sortedProducts); 
}

//java
public void linq37(){
    List<Product> products = getProductList();

    List<Product> sortedProducts = orderByAll(products,
        new Comparator<Product>() {
            @Override
            public int compare(Product a, Product b) {
                return a.category.compareTo(b.category);
            }
        },
        new Comparator<Product>() {
            @Override
            public int compare(Product a, Product b) {
                return b.unitPrice.compareTo(a.unitPrice);
            }
        }
    );

    for (Product p : sortedProducts){
        Log.d(p);
    }
}

(Product id=38, name=Côte de Blaye, cat=Beverages, price=263.5, inStock=17)
(Product id=43, name=Ipoh Coffee, cat=Beverages, price=46.0, inStock=17)
(Product id=2, name=Chang, cat=Beverages, price=19.0, inStock=17)
(Product id=1, name=Chai, cat=Beverages, price=18.0, inStock=39)
(Product id=35, name=Steeleye Stout, cat=Beverages, price=18.0, inStock=20)
(Product id=39, name=Chartreuse verte, cat=Beverages, price=18.0, inStock=69)
(Product id=76, name=Lakkalikööri, cat=Beverages, price=18.0, inStock=57)
(Product id=70, name=Outback Lager, cat=Beverages, price=15.0, inStock=15)
(Product id=34, name=Sasquatch Ale, cat=Beverages, price=14.0, inStock=111)
...

//c#
public void Linq38() 
{ 
    string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" }; 
  
    var sortedWords = 
        words.OrderBy(a => a.Length) 
             .ThenByDescending(a => a, new CaseInsensitiveComparer()); 
  
    ObjectDumper.Write(sortedWords); 
} 

//java
public void linq38(){
    String[] words = new String[] { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

    List<String> sortedWords = orderByAll(words,
        new Comparator<String>() {
            @Override
            public int compare(String a, String b) {
                return Integer.compare(a.length(), b.length());
            }
        },
        new Comparator<String>() {
            @Override
            public int compare(String a, String b) {
                return String.CASE_INSENSITIVE_ORDER.compare(b,a);
            }
        });

    for (String w : sortedWords){
        Log.d(w);
    }
}

aPPLE
ClOvEr
cHeRry
bRaNcH
AbAcUs
BlUeBeRrY

//c#
public void Linq39() 
{ 
    string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    var reversedIDigits = ( 
        from d in digits 
        where d[1] == 'i' 
        select d) 
        .Reverse(); 
  
    Console.WriteLine("A backwards list of the digits with a second character of 'i':"); 
    foreach (var d in reversedIDigits) 
    { 
        Console.WriteLine(d); 
    } 
}

//java
public void linq39(){
    String[] digits = new String[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

    List<String> reversedIDigits = reverse(filter(digits, new Predicate<String>() {
        @Override
        public boolean apply(String d) {
            return d.charAt(1) == 'i';
        }
    }));

    Log.d("A backwards list of the digits with a second character of 'i':");
    for (String d : reversedIDigits){
        Log.d(d);
    }
}

A backwards list of the digits with a second character of 'i':
nine
eight
six
five

//c#
public void Linq40() 
{ 
    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 
  
    var numberGroups = 
        from n in numbers 
        group n by n % 5 into g 
        select new { Remainder = g.Key, Numbers = g }; 
  
    foreach (var g in numberGroups) 
    { 
        Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder); 
        foreach (var n in g.Numbers) 
        { 
            Console.WriteLine(n); 
        } 
    } 
}

//java
public void linq40(){
    int[] numbers = new int[] { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    List<Tuple<Integer, Group<Integer,Integer>>> numberGroups = map(
        groupBy(toList(numbers), new Function<Integer, Integer>() {
            @Override
            public Integer apply(Integer n){
                return n % 5;
            }
        }),
        new Function<Group<Integer, Integer>, Tuple<Integer, Group<Integer,Integer>>>() {
            @Override
            public Tuple<Integer, Group<Integer,Integer>> apply(Group<Integer, Integer> g){
                return new Tuple<>(g.key, g);
            }
        });

    for (Tuple<Integer, Group<Integer,Integer>> g : numberGroups){
        Log.d("Numbers with a remainder of " + g.A + " when divided by 5:");
        for (Integer n : g.B){
            Log.d(n);
        }
    }
}

Numbers with a remainder of 4 when divided by 5:
4
9
Numbers with a remainder of 1 when divided by 5:
1
6
Numbers with a remainder of 0 when divided by 5:
5
0
Numbers with a remainder of 2 when divided by 5:
7
2
Numbers with a remainder of 3 when divided by 5:
3
8

//c#
public void Linq41() 
{ 
    string[] words = { "blueberry", "chimpanzee", "abacus", "banana", "apple", "cheese" }; 
  
    var wordGroups = 
        from w in words 
        group w by w[0] into g 
        select new { FirstLetter = g.Key, Words = g }; 
  
    foreach (var g in wordGroups) 
    { 
        Console.WriteLine("Words that start with the letter '{0}':", g.FirstLetter); 
        foreach (var w in g.Words) 
        { 
            Console.WriteLine(w); 
        } 
    } 
}

//java
public void linq41(){
    String[] words = new String[] { "blueberry", "chimpanzee", "abacus", "banana", "apple", "cheese" };

    List<Tuple<Character, Group<Character,String>>> wordGroups = map(
        groupBy(toList(words), new Function<String, Character>() {
            @Override
            public Character apply(String s){
                return s.charAt(0);
            }
        }),
        new Function<Group<Character, String>, Tuple<Character, Group<Character,String>>>() {
            @Override
            public Tuple<Character, Group<Character,String>> apply(Group<Character,String> g){
                return new Tuple<>(g.key, g);
            }
        });

    for (Tuple<Character, Group<Character,String>> g : wordGroups){
        Log.d("Words that start with the letter '" + g.A + "':");
        for (String w : g.B){
            Log.d(w);
        }
    }
}

Words that start with the letter 'a':
abacus
apple
Words that start with the letter 'b':
blueberry
banana
Words that start with the letter 'c':
chimpanzee
cheese

//c#
public void Linq42() 
{ 
    List<Product> products = GetProductList(); 
  
    var orderGroups = 
        from p in products 
        group p by p.Category into g 
        select new { Category = g.Key, Products = g }; 
  
    ObjectDumper.Write(orderGroups, 1); 
} 

//java
public void linq42(){
    List<Product> products = getProductList();

    List<Tuple<String,Group<String,Product>>> orderGroups = map(
        groupBy(products, new Function<Product, String>() {
            @Override
            public String apply(Product p){
                return p.category;
            }
        }),
        new Function<Group<String,Product>, Tuple<String, Group<String,Product>>>() {
            @Override
            public Tuple<String, Group<String,Product>> apply(Group<String,Product> g){
                return new Tuple<>(g.key, g);
            }
        });

    for (Tuple<String,Group<String,Product>> x : orderGroups){
        Log.d(x.B);
    }
}

Confections:
(Product id=16, name=Pavlova, cat=Confections, price=17.45, inStock=29)
(Product id=19, name=Teatime Chocolate Biscuits, cat=Confections, price=9.2, inStock=25)
(Product id=20, name=Sir Rodney's Marmalade, cat=Confections, price=81.0, inStock=40)
(Product id=21, name=Sir Rodney's Scones, cat=Confections, price=10.0, inStock=3)
(Product id=25, name=NuNuCa Nuß-Nougat-Creme, cat=Confections, price=14.0, inStock=76)
(Product id=26, name=Gumbär Gummibärchen, cat=Confections, price=31.23, inStock=15)
(Product id=27, name=Schoggi Schokolade, cat=Confections, price=43.9, inStock=49)
(Product id=47, name=Zaanse koeken, cat=Confections, price=9.5, inStock=36)
(Product id=48, name=Chocolade, cat=Confections, price=12.75, inStock=15)
(Product id=49, name=Maxilaku, cat=Confections, price=20.0, inStock=10)
(Product id=50, name=Valkoinen suklaa, cat=Confections, price=16.25, inStock=65)
(Product id=62, name=Tarte au sucre, cat=Confections, price=49.3, inStock=17)
(Product id=68, name=Scottish Longbreads, cat=Confections, price=12.5, inStock=6)

Seafood:
(Product id=10, name=Ikura, cat=Seafood, price=31.0, inStock=31)
(Product id=13, name=Konbu, cat=Seafood, price=6.0, inStock=24)

//c#
public void Linq43() 
{ 
    List<Customer> customers = GetCustomerList(); 
  
    var customerOrderGroups = 
        from c in customers 
        select 
            new 
            { 
                c.CompanyName, 
                YearGroups = 
                    from o in c.Orders 
                    group o by o.OrderDate.Year into yg 
                    select 
                        new 
                        { 
                            Year = yg.Key, 
                            MonthGroups = 
                                from o in yg 
                                group o by o.OrderDate.Month into mg 
                                select new { Month = mg.Key, Orders = mg } 
                        } 
            }; 
  
    ObjectDumper.Write(customerOrderGroups, 3); 
} 

//java
public void linq43(){
    List<Customer> customers = getCustomerList();

    List<Tuple<String, ArrayList<Tuple<Integer, ArrayList<Group<Integer, Order>>>>>> customerOrderGroups =
        map(customers, new Function<Customer, Tuple<String, ArrayList<Tuple<Integer, ArrayList<Group<Integer, Order>>>>>>() {
            @Override
            public Tuple<String, ArrayList<Tuple<Integer, ArrayList<Group<Integer, Order>>>>> apply(Customer c) {
                return new Tuple<>( //Yay Type Inference!
                    c.companyName,
                    map(groupBy(c.orders, new Function<Order, Integer>() {
                            @Override
                            public Integer apply(Order o) {
                                return o.orderDate.getYear() + 1900;
                            }
                        }),
                        new Function<Group<Integer, Order>, Tuple<Integer, ArrayList<Group<Integer, Order>>>>() {
                            @Override
                            public Tuple<Integer, ArrayList<Group<Integer, Order>>> apply(Group<Integer, Order> yg) {
                                return new Tuple<>( //Yay Type Inference!
                                    yg.key,
                                    groupBy(yg.items, new Function<Order, Integer>() {
                                        @Override
                                        public Integer apply(Order o) {
                                            return o.orderDate.getMonth() + 1;
                                        }
                                    })
                                );
                            }
                        }
                    )
                );
            }
        });

    for (Tuple<String, ArrayList<Tuple<Integer, ArrayList<Group<Integer, Order>>>>> g : customerOrderGroups){
        Log.d("\n# " + g.A);
        for (Tuple<Integer, ArrayList<Group<Integer, Order>>> yg : g.B){
            Log.d(yg.A + ": ");
            for (Group<Integer, Order> mg : yg.B){
                Log.d("  " + mg.key + ": ");
                for (Order o : mg){
                    Log.d("    " + o);
                }
            }
        }
    }
}

# Alfreds Futterkiste
1997: 
  8: 
    (Order id=10643, total=814.5)
  10: 
    (Order id=10692, total=878.0)
    (Order id=10702, total=330.0)
1998: 
  4: 
    (Order id=11011, total=933.5)
  1: 
    (Order id=10835, total=845.8)
  3: 
    (Order id=10952, total=471.2)

//c#
public void Linq44() 
{ 
    string[] anagrams = { "from   ", " salt", " earn ", "  last   ", " near ", " form  " }; 
  
    var orderGroups = anagrams.GroupBy(w => w.Trim(), new AnagramEqualityComparer()); 
  
    ObjectDumper.Write(orderGroups, 1); 
} 

//java
public void linq44(){
    String[] anagrams = new String[] { "from   ", " salt", " earn ", "  last   ", " near ", " form  " };

    List<Group<String, String>> orderGroups = groupBy(toList(anagrams),
            new Function<String, String>() {
                @Override
                public String apply(String w) {
                    return w.trim();
                }
            },
            new Predicate2<String, String>() {
                @Override
                public boolean apply(String a, String b) {
                    char[] aChars = a.toCharArray();
                    char[] bChars = b.toCharArray();
                    Arrays.sort(aChars);
                    Arrays.sort(bChars);
                    return Arrays.equals(aChars, bChars);
                }
            });

    for (Group<String, String> g : orderGroups){
        StringBuilder sb = new StringBuilder();
        for (String w : g){
            if (sb.length() > 0)
                sb.append(", ");

            sb.append("'").append(w).append("'");
        }
        Log.d("[ " + sb + " ]");
    }
}

[ ' earn ', ' near ' ]
[ ' salt', '  last   ' ]
[ 'from   ', ' form  ' ]

//c#
public void Linq45() 
{ 
    string[] anagrams = { "from   ", " salt", " earn ", "  last   ", " near ", " form  " }; 
  
    var orderGroups = anagrams.GroupBy( 
                w => w.Trim(), 
                a => a.ToUpper(), 
                new AnagramEqualityComparer() 
                ); 
  
    ObjectDumper.Write(orderGroups, 1); 
} 

//java
public void linq45(){
    String[] anagrams = new String[] { "from   ", " salt", " earn ", "  last   ", " near ", " form  " };

    List<Group<String, String>> orderGroups = groupBy(toList(anagrams),
            new Function<String, String>() {
                @Override
                public String apply(String w) {
                    return w.trim();
                }
            },
            new Predicate2<String, String>() {
                @Override
                public boolean apply(String a, String b) {
                    char[] aChars = a.toCharArray();
                    char[] bChars = b.toCharArray();
                    Arrays.sort(aChars);
                    Arrays.sort(bChars);
                    return Arrays.equals(aChars, bChars);
                }
            },
            new Function<String, String>() {
                @Override
                public String apply(String s) {
                    return s.toUpperCase();
                }
            });

    for (Group<String, String> g : orderGroups){
        StringBuilder sb = new StringBuilder();
        for (String w : g){
            if (sb.length() > 0)
                sb.append(", ");

            sb.append("'").append(w).append("'");
        }
        Log.d("[ " + sb + " ]");
    }
}

[ ' EARN ', ' NEAR ' ]
[ ' SALT', '  LAST   ' ]
[ 'FROM   ', ' FORM  ' ]

//c#
public void Linq46() 
{ 
    int[] factorsOf300 = { 2, 2, 3, 5, 5 }; 
  
    var uniqueFactors = factorsOf300.Distinct(); 
  
    Console.WriteLine("Prime factors of 300:"); 
    foreach (var f in uniqueFactors) 
    { 
        Console.WriteLine(f); 
    } 
}

//java
public void linq46(){
    int[] factorsOf300 = new int[] { 2, 2, 3, 5, 5 };

    List<Integer> uniqueFactors = distinct(toList(factorsOf300));

    Log.d("Prime factors of 300:");
    for (Integer f : uniqueFactors){
        Log.d(f);
    }
}

Prime factors of 300:
5
3
2

//c#
public void Linq47() 
{ 
    List<Product> products = GetProductList(); 
  
    var categoryNames = ( 
        from p in products 
        select p.Category) 
        .Distinct(); 
  
    Console.WriteLine("Category names:"); 
    foreach (var n in categoryNames) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq47(){
    List<Product> products = getProductList();

    List<String> categoryNames = distinct(
        map(products, new Function<Product, String>() {
            @Override
            public String apply(Product p) {
                return p.category;
            }
        }));

    Log.d("Category names:");
    for (String n : categoryNames){
        Log.d(n);
    }
}

Category names:
Confections
Seafood
Grains/Cereals
Meat/Poultry
Beverages
Condiments
Dairy Products
Produce

//c#
public void Linq48() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 
  
    var uniqueNumbers = numbersA.Union(numbersB); 
  
    Console.WriteLine("Unique numbers from both arrays:"); 
    foreach (var n in uniqueNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq48(){
    int[] numbersA = new int[] { 0, 2, 4, 5, 6, 8, 9 };
    int[] numbersB = new int[] { 1, 3, 5, 7, 8 };

    List<Integer> uniqueNumbers = union(toList(numbersA), toList(numbersB));

    Log.d("Unique numbers from both arrays:");
    for (Integer n : uniqueNumbers){
        Log.d(n);
    }
}

Unique numbers from both arrays:
0
2
4
5
6
8
9
1
3
7

//c#
public void Linq49() 
{ 
    List<Product> products = GetProductList(); 
    List<Customer> customers = GetCustomerList(); 
  
    var productFirstChars = 
        from p in products 
        select p.ProductName[0]; 
    var customerFirstChars = 
        from c in customers 
        select c.CompanyName[0]; 
  
    var uniqueFirstChars = productFirstChars.Union(customerFirstChars); 
  
    Console.WriteLine("Unique first letters from Product names and Customer names:"); 
    foreach (var ch in uniqueFirstChars) 
    { 
        Console.WriteLine(ch); 
    } 
}

//java
public void linq49(){
    List<Product> products = getProductList();
    List<Customer> customers = getCustomerList();

    List<Character> productFirstChars = map(products, new Function<Product, Character>() {
        @Override
        public Character apply(Product p) {
            return p.productName.charAt(0);
        }
    });

    List<Character> customerFirstChars = map(customers, new Function<Customer, Character>() {
        @Override
        public Character apply(Customer c) {
            return c.companyName.charAt(0);
        }
    });

    List<Character> uniqueFirstChars = union(productFirstChars, customerFirstChars);

    Log.d("Unique first letters from Product names and Customer names:");
    for (Character ch : uniqueFirstChars){
        Log.d(ch);
    }
}

Unique first letters from Product names and Customer names:
C
A
G
U
N
M
I
Q
K
T
P
S
R
B
J
Z
V
F
E
W
L
O
D
H

//c#
public void Linq50() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 
  
    var commonNumbers = numbersA.Intersect(numbersB); 
  
    Console.WriteLine("Common numbers shared by both arrays:"); 
    foreach (var n in commonNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq50(){
    int[] numbersA = new int[] { 0, 2, 4, 5, 6, 8, 9 };
    int[] numbersB = new int[] { 1, 3, 5, 7, 8 };

    List<Integer> commonNumbers = intersect(toList(numbersA), toList(numbersB));

    Log.d("Common numbers shared by both arrays:");
    for (Integer n : commonNumbers){
        Log.d(n);
    }
}

Common numbers shared by both arrays:
5
8

//c#
public void Linq51() 
{ 
    List<Product> products = GetProductList(); 
    List<Customer> customers = GetCustomerList(); 
  
    var productFirstChars = 
        from p in products 
        select p.ProductName[0]; 
    var customerFirstChars = 
        from c in customers 
        select c.CompanyName[0]; 
  
    var commonFirstChars = productFirstChars.Intersect(customerFirstChars); 
  
    Console.WriteLine("Common first letters from Product names and Customer names:"); 
    foreach (var ch in commonFirstChars) 
    { 
        Console.WriteLine(ch); 
    } 
}

//java
public void linq51(){
    List<Product> products = getProductList();
    List<Customer> customers = getCustomerList();

    List<Character> productFirstChars = map(products, new Function<Product, Character>() {
        @Override
        public Character apply(Product p) {
            return p.productName.charAt(0);
        }
    });

    List<Character> customerFirstChars = map(customers, new Function<Customer, Character>() {
        @Override
        public Character apply(Customer c) {
            return c.companyName.charAt(0);
        }
    });

    List<Character> commonFirstChars = intersect(productFirstChars, customerFirstChars);

    Log.d("Common first letters from Product names and Customer names:");
    for (Character ch : commonFirstChars){
        Log.d(ch);
    }
}

Common first letters from Product names and Customer names:
C
A
G
N
M
I
Q
K
T
P
S
R
B
V
F
E
W
L
O

//c#
public void Linq52() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 
  
    IEnumerable<int> aOnlyNumbers = numbersA.Except(numbersB); 
  
    Console.WriteLine("Numbers in first array but not second array:"); 
    foreach (var n in aOnlyNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

//java
public void linq52(){
    int[] numbersA = new int[] { 0, 2, 4, 5, 6, 8, 9 };
    int[] numbersB = new int[] { 1, 3, 5, 7, 8 };

    List<Integer> aOnlyNumbers = difference(toList(numbersA), toList(numbersB));

    Log.d("Numbers in first array but not second array:");
    for(Integer n: aOnlyNumbers){
        Log.d(n);
    }
}

Numbers in first array but not second array:
0
2
4
6
9

//c#
public void Linq53() 
{ 
    List<Product> products = GetProductList(); 
    List<Customer> customers = GetCustomerList(); 
  
    var productFirstChars = 
        from p in products 
        select p.ProductName[0]; 
    var customerFirstChars = 
        from c in customers 
        select c.CompanyName[0]; 
  
    var productOnlyFirstChars = productFirstChars.Except(customerFirstChars); 
  
    Console.WriteLine("First letters from Product names, but not from Customer names:"); 
    foreach (var ch in productOnlyFirstChars) 
    { 
        Console.WriteLine(ch); 
    } 
}

//java
public void linq53(){
    List<Product> products = getProductList();
    List<Customer> customers = getCustomerList();

    List<Character> productFirstChars = map(products, new Function<Product, Character>() {
        @Override
        public Character apply(Product p) {
            return p.productName.charAt(0);
        }
    });

    List<Character> customerFirstChars = map(customers, new Function<Customer, Character>() {
        @Override
        public Character apply(Customer c) {
            return c.companyName.charAt(0);
        }
    });

    List<Character> productOnlyFirstChars = difference(productFirstChars, customerFirstChars);

    Log.d("First letters from Product names, but not from Customer names:");
    for (Character ch : productOnlyFirstChars){
        Log.d(ch);
    }
}

First letters from Product names, but not from Customer names:
U
J
Z

//c#
public void Linq54() 
{ 
    double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 }; 
  
    var sortedDoubles = 
        from d in doubles 
        orderby d descending 
        select d; 
    var doublesArray = sortedDoubles.ToArray(); 
  
    Console.WriteLine("Every other double from highest to lowest:"); 
    for (int d = 0; d < doublesArray.Length; d += 2) 
    { 
        Console.WriteLine(doublesArray[d]); 
    } 
}

//java
public void linq54(){
    double[] doubles = new double[] { 1.7, 2.3, 1.9, 4.1, 2.9 };

    List<Double> sortedDoubles = orderByDesc(toList(doubles));

    Double[] doublesArray = toArray(sortedDoubles, Double.class);

    Log.d("Every other double from highest to lowest:");
    for (int d = 0; d < doublesArray.length; d += 2){
        Log.d(doublesArray[d]);
    }
}

Every other double from highest to lowest:
4.1
2.3
1.7

//c#
public void Linq55() 
{ 
    string[] words = { "cherry", "apple", "blueberry" }; 
  
    var sortedWords = 
        from w in words 
        orderby w 
        select w; 
    var wordList = sortedWords.ToList(); 
  
    Console.WriteLine("The sorted word list:"); 
    foreach (var w in wordList) 
    { 
        Console.WriteLine(w); 
    } 
}

//java
public void linq55(){
    String[] words = new String[] { "cherry", "apple", "blueberry" };

    List<String> sortedWords = orderBy(words);
    List<String> wordList = toList(sortedWords);

    Log.d("The sorted word list:");
    for (String w : wordList){
        Log.d(w);
    }
}

The sorted word list:
apple
blueberry
cherry

//c#
public void Linq56() 
{ 
    var scoreRecords = new[] { new {Name = "Alice", Score = 50}, 
                                new {Name = "Bob"  , Score = 40}, 
                                new {Name = "Cathy", Score = 45} 
                            }; 
  
    var scoreRecordsDict = scoreRecords.ToDictionary(sr => sr.Name); 
  
    Console.WriteLine("Bob's score: {0}", scoreRecordsDict["Bob"]); 
}

//java
public void linq56(){
    List<Tuple<String,Integer>> scoreRecords = toList(
        new Tuple<>("Alice", 50),
        new Tuple<>("Bob", 40),
        new Tuple<>("Cathy", 45)
    );

    Map<String,Tuple<String,Integer>> scoreRecordsDict = toDictionary(scoreRecords, new Function<Tuple<String, Integer>, String>() {
        @Override
        public String apply(Tuple<String, Integer> t) {
            return t.A;
        }
    });

    Log.d("Bob's score: " + scoreRecordsDict.get("Bob"));
}

//c#
public void Linq57() 
{ 
    object[] numbers = { null, 1.0, "two", 3, "four", 5, "six", 7.0 }; 
  
    var doubles = numbers.OfType<double>(); 
  
    Console.WriteLine("Numbers stored as doubles:"); 
    foreach (var d in doubles) 
    { 
        Console.WriteLine(d); 
    } 
}

//java
public void linq57(){
    Object[] numbers = new Object[] { null, 1.0, "two", 3, "four", 5, "six", 7.0 };

    List<Double> doubles = ofType(toList(numbers), Double.class);

    Log.d("Numbers stored as doubles:");
    for (Double d : doubles){
        Log.d(d);
    }
}

Numbers stored as doubles:
1.0
7.0

//c#
public void Linq58() 
{ 
    List<Product> products = GetProductList(); 
 
    Product product12 = ( 
        from p in products 
        where p.ProductID == 12 
        select p) 
        .First(); 
  
    ObjectDumper.Write(product12); 
}

//java
public void linq58(){
    List<Product> products = getProductList();

    Product product12 = first(products, new Predicate<Product>() {
        @Override
        public boolean apply(Product p) {
            return p.productId == 12;
        }
    });

    Log.d(product12);
}

(Product id=12, name=Queso Manchego La Pastora, cat=Dairy Products, price=38.0, inStock=86)

//c#
public void Linq59() 
{ 
    string[] strings = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" }; 
  
    string startsWithO = strings.First(s => s[0] == 'o'); 
  
    Console.WriteLine("A string starting with 'o': {0}", startsWithO); 
}