RetroSearch Browse

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://www.geeksforgeeks.org/java/java-collection-exercise/ below:

Java Collection Exercise - GeeksforGeeks

The Java Collection framework is a fundamental part of the Java programming language, It covers a major part of Java and acts as a prerequisite for many Advanced Java Topics.

What is Collection in Java?

Collection Framework in Java contains a Set of Interfaces and Classes to represent groups of objects as a Single Unit. In Java, the Collection interface (java.util.Collection) and Map interface (java.util.Map) are the two main “root” interfaces of Java collection classes.

Basic Programs

Want to solidify your Java collection skills? Here's your chance! Get hands-on with these basic practice programs in Java Collection. Work with common collections like ArrayLists and HashSets, all while strengthening your Java coding abilities.

1. How to Print a Collection in Java? Java


 import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        String[] geeks = { "Rahul", "Utkarsh", "Shubham", "Neelam" };

        List<String> al = new ArrayList<String>();

        // adding elements of array to arrayList.
        Collections.addAll(al, geeks);
        System.out.println(al);
    }
}

Output

[Rahul, Utkarsh, Shubham, Neelam]

More Examples as Solution

2. How to Make a Collection Read-Only in Java? Java


 import java.util.Set;
import java.util.HashSet;
import java.util.Collections;

class GFG {
    public static void main(String[] args)
    {
        // Set of Integer
        Set<Integer> numbers = new HashSet<Integer>();

        // Set have 1 to 10 numbers
        for (int i = 1; i <= 5; i++) {
            numbers.add(i);
        }

        // print the integers
        numbers.stream().forEach(System.out::print);
        // Removing element from the list
        numbers.remove(5);

        System.out.println("\nAfter Performing Operation");
        numbers.stream().forEach(System.out::print);
        System.out.println("\nSet is also By Default Readable and Writable");

        // Now making Read-Only Set using unmodifiableSet() method.
        try {
            numbers = Collections.unmodifiableSet(numbers);

            // This line will generate an Exception
            numbers.remove(4);
        }
        catch (UnsupportedOperationException unsupportedOperationException) {
            System.out.println("Exceptions is " + unsupportedOperationException);
        }
        finally {
            System.out.println(numbers.contains(3));
            System.out.println("Now Set is Read-Only");
        }
    }
}

Output

12345
After Performing Operation
1234
Set is also By Default Readable and Writable
Exceptions is java.lang.UnsupportedOperationException
true
Now Set is Read-Only

Other Alternative Solutions

3. Java Program to Compare Elements in a Collection.

Input : List = [3, 5, 18, 4, 6]
Output: Min value of our list : 3
Max value of our list : 18
Explanation: Comparison lead to result that the min of the list is 3 and max of list is 18. Similarly we can test for other Collections too.