Last Updated : 25 Jul, 2019
Stream.min()returns the minimum element of the stream based on the provided Comparator. A Comparator is a comparison function, which imposes a total ordering on some collection of objects. min() is a
terminal operationwhich combines stream elements and returns a summary result. So, min() is a special case of reduction. The method returns Optional instance.
Syntax :Optional<T> min(Comparator<? super T> comparator) Where, Optional is a container object which may or may not contain a non-null value and T is the type of objects that may be compared by this comparatorException :
This method throws
NullPointerExceptionif the minimum element is null.
Example 1 :Minimum from list of Integers.
Java
// Java code for Stream.min() method to get
// the minimum element of the Stream
// according to the provided Comparator.
import java.util.*;
class GFG {
// Driver code
public static void main(String[] args)
{
// Creating a list of integers
List<Integer> list = Arrays.asList(-9, -18, 0, 25, 4);
// Using stream.min() to get minimum
// element according to provided Integer Comparator
Integer var = list.stream().min(Integer::compare).get();
System.out.print(var);
}
}
Output :
-18Example 2 :
Reverse comparator to get maximum value using min() function.
Java
// Java code for Stream.min() method
// to get the minimum element of the
// Stream according to provided comparator.
import java.util.*;
class GFG {
// Driver code
public static void main(String[] args)
{
// Creating a list of integers
List<Integer> list = Arrays.asList(-9, -18, 0, 25, 4);
// Using Stream.min() with reverse
// comparator to get maximum element.
Optional<Integer> var = list.stream()
.min(Comparator.reverseOrder());
// IF var is empty, then output will be Optional.empty
// else value in var is printed.
if(var.isPresent()){
System.out.println(var.get());
}
else{
System.out.println("NULL");
}
}
}
Output :
25Example 3 :
Comparing strings based on last characters.
Java
// Java code for Stream.min() method
// to get the minimum element of the
// Stream according to provided comparator.
import java.util.*;
class GFG {
// Driver code
public static void main(String[] args)
{
// creating an array of strings
String[] array = { "Geeks", "for", "GeeksforGeeks",
"GeeksQuiz" };
// The Comparator compares the strings
// based on their last characters and returns
// the minimum value accordingly.
Optional<String> MIN = Arrays.stream(array).min((str1, str2) ->
Character.compare(str1.charAt(str1.length() - 1),
str2.charAt(str2.length() - 1)));
// If a value is present,
// isPresent() will return true
if (MIN.isPresent())
System.out.println(MIN.get());
else
System.out.println("-1");
}
}
Output :
for
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