Comparator reverseOrder() method in Java with examples

The reverseOrder() method of Comparator Interface in Java returns a comparator that use to compare Comparable objects in reverse of natural order. The returned comparator by this method is serializable and throws NullPointerException when comparing null. 

Syntax:

static <T extends Comparable<T>> 
    Comparator<T> reverseOrder()

Parameters: This method accepts nothing. 

Return value: This method returns a comparator that imposes the reverse natural ordering on Comparable objects. 

Below programs illustrate reverseOrder() method: 

Program 1:

Java

// Java program to demonstrate
// Comparator.reverseOrder()  method

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

public class GFG {
    public static void main(String... args)
    {

        List<Integer> values
            = Arrays.asList(212, 324,
                            435, 566,
                            133, 100,
                            121);

        // reverseOrder is a static method
        values.sort(Comparator.reverseOrder());

        // print sorted number based on reverse order
        System.out.println(values);
    }
}

The output printed on console of IDE is shown below. 

Output:

Program 2:

Java

// Java program to demonstrate
// Comparator.reverseOrder()  method

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;

public class GFG {
    public static void main(String... args)
    {

        List<String> stringList
            = Arrays.asList("Aman", "Kajal",
                            "Joyita", "Das");

        System.out.println("Before sorting:");
        stringList.forEach(System.out::println);

        stringList.sort(Comparator.reverseOrder());
        System.out.println("\nAfter sorting:");
        stringList.forEach(System.out::println);
    }
}

The output printed on console is shown below. 

Output:

References: https://docs.oracle.com/javase/10/docs/api/java/util/Comparator.html#reverseOrder()