Stream.max() returns the maximum 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. max() is a terminal operation which combines stream elements and returns a summary result. So, max() is a special case of reduction. The method returns Optional instance.
Syntax :
Optional<T> max(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 comparator
Exception : This method throws NullPointerException if the maximum element is null.
Example 1 :
// Implementation of Stream.max() // to get the maximum element // of the Stream according to the // provided Comparator. import java.util.*;
import java.util.Optional;
import java.util.Comparator;
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 );
System.out.print( "The maximum value is : " );
// Using stream.max() to get maximum
// element according to provided Comparator
// and storing in variable var
Integer var = list.stream().max(Integer::compare).get();
System.out.print(var);
}
} |
Output :
The maximum value is : 25
Example 2 :
// Implementation of Stream.max() // to get the maximum element // of the Stream according to the // provided Comparator. import java.util.*;
import java.util.Optional;
import java.util.Comparator;
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.max() to get maximum
// element according to provided Comparator
// Here, the smallest element in list
// will be stored in variable var
Optional<Integer> var = list.stream()
.max(Comparator.reverseOrder());
// If a value is present, isPresent()
// will return true, else display message
if (var.isPresent()) {
System.out.println(var.get());
}
else {
System.out.println( "-1" );
}
}
} |
Output :
-18
Example 3 :
// Implementation of Stream.max() // to get the maximum element // of the Stream according to the // provided Comparator. import java.util.*;
import java.util.Optional;
import java.util.Comparator;
class GFG {
// Driver code
public static void main(String[] args)
{
// Creating a list of Strings
List<String> list = Arrays.asList( "G" , "E" , "E" , "K" ,
"g" , "e" , "e" , "k" );
// using Stream.max() method with Comparator
// Here, the character with maximum ASCII value
// is stored in variable MAX
String MAX = list.stream().max(Comparator.
comparing(String::valueOf)).get();
// Displaying the maximum element in
// the stream according to provided Comparator
System.out.println( "Maximum element in the "
+ "stream is : " + MAX);
}
} |
Output :
Maximum element in the stream is : k
Example 4 :
// Implementation of Stream.max() // to get the maximum element // of the Stream according to the // provided Comparator. import java.util.*;
import java.util.Optional;
import java.util.Comparator;
class GFG {
// Driver code
public static void main(String[] args)
{
// creating an array of strings
String[] array = { "Geeks" , "for" , "GeeksforGeeks" ,
"GeeksQuiz" };
// Here, the Comparator compares the strings
// based on their last characters and returns
// the maximum value accordingly
// The result is stored in variable MAX
Optional<String> MAX = Arrays.stream(array).max((str1, str2) ->
Character.compare(str1.charAt(str1.length() - 1 ),
str2.charAt(str2.length() - 1 )));
// If a value is present,
// isPresent() will return true
if (MAX.isPresent())
System.out.println(MAX.get());
else System.out.println( "-1" );
}
} |
Output :
GeeksQuiz