Java Collections reverseOrder() Method

The reverseOrder() is a Java Collections class method which returns a comparator that imposes the reverse of the natural ordering on the objects. There is two different types of Java reverseOrder() method which can be differentiated depending on its parameter. These are:

Java Collections reverseOrder() Method
Java Collections reverseOrder(comp) Method

Java Collections reverseOrder() Method

The reverseOrder() method of Java Collections class is used to get the comparator that imposes the reverse of the natural ordering on a collection of objects which implement the Comparable interface.

Java Collections reverseOrder(comp) Method

The reverseOrder() method of Java Collections class is used to get the comparator that imposes the reverse ordering of the specified comparator.

Syntax

Following is the declaration of reverseOrder() method:

  public static  Comparator reverseOrder()  public static  Comparator reverseOrder(Comparator comp)  

Parameter

Parameter	Description	Required/Optional
comp	It is a comparator whose ordering is to be reversed by the returned comparator or null.	Required

Returns

Method	Returns
reverseOrder()	It returns a comparator that imposes the reverse natural ordering on a collection of objects that implement the Comparable interface.
reverseOrder(Comparator comp)	It returns a comparator that imposes the reverse ordering of the specified comparator.

Exceptions

Compatibility Version

Java 1.5 and above

Example 1

  import java.util.*;  public class CollectionsReverseOrderExample1 {  public static void main(String[] args) {         //Create linked list object        LinkedList list = new LinkedList();        //Add values in the list        list.add(10);        list.add(-20);        list.add(50);        list.add(90);        list.add(-15);        //Sort the list and return comparator for reverse order        Collections.sort(list, Collections.reverseOrder());          System.out.println(“List sorted in ReverseOrder: “);        System.out.println(list);        }  }  

Test it Now

Output:

List sorted in ReverseOrder:   [90, 50, 10, -15, -20]

Example 2

  import java.util.*;  public class CollectionsReverseOrderExample2 {  public static void main(String[] args) {         //Create Array list object  List list = Arrays.asList(“Java”, “Python”, “Ruby”, “COBOL”);              Collections.sort(list, Collections.reverseOrder());        System.out.println(“List sorted in ReverseOrder: “);        System.out.println(list);        }  }  

Test it Now

Output:

List sorted in ReverseOrder:   [Ruby, Python, Java, COBOL]

Example 3

  import java.util.*;  public class CollectionsReverseOrderExample3 {  public static void main(String[] args) {         //Create Array list object  List list = Arrays.asList(“Jaya”, “Pratham”, “Ruby”, “Commit”);  Collections.sort(list, Collections.reverseOrder (CollectionsReverseOrderExample3::lastCharComparator));  //Sort the list according to last character of word and return comparator for reverse order          System.out.println(list);          }  private static int lastCharComparator(String s1, String s2) {  return Character.compare(s1.charAt(s1.length() – 1), s2.charAt(s2.length()-1));  }  }  

Test it Now

Output:

[Ruby, Commit, Pratham, Jaya]

Example 4

  import java.util.*;  public class CollectionsReverseOrderExample4 {  public static void main(String[] args) {         //Create linked list object             LinkedList list = new LinkedList();          //Add values in the list         list.add(50);          list.add(-20);          list.add(120);          list.add(-80);          //Sort the list and Create comparator for reverse order        Comparator cmp = Collections.reverseOrder(null);          Collections.sort(list, cmp);          //Print the list        System.out.println(“List sorted in ReverseOrder: “);              for(int i : list) {           System.out.println(i+ ” “);        }  }  }  

Test it Now

Output:

List sorted in ReverseOrder:   120   50   -20   -80

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Java Collections reverseOrder() Method with Examples

Java Collections reverseOrder() Method

Java Collections reverseOrder() Method

Java Collections reverseOrder(comp) Method

Syntax

Parameter

Returns

Exceptions

Compatibility Version

Example 1

Example 2

Example 3

Example 4

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