Java: Get a reverse order view of the keys contained in a given map

Last update on March 12 2025 13:34:05 (UTC/GMT +8 hours)

Write a Java program to get a reverse order view of the keys contained in a given map.

Sample Solution:-

Java Code:

import java.util.*;
import java.util.Map.Entry;  
public class Example10 {  
     public static void main(String args[]) {

  // Create a tree map
  TreeMap <String,String> tree_map1 = new TreeMap <String,String> ();

  // Put elements to the map 
  tree_map1.put("C2", "Red");
  tree_map1.put("C1", "Green");
  tree_map1.put("C4", "Black");
  tree_map1.put("C3", "White");

  System.out.println("Orginal TreeMap content: " + tree_map1);
  System.out.println("Reverse order view of the keys: " + tree_map1.descendingKeySet());
 }
}

Sample Output:

Orginal TreeMap content: {C1=Green, C2=Red, C3=White, C4=Black}        
Reverse order view of the keys: [C4, C3, C2, C1]

For more Practice: Solve these Related Problems:

• Write a Java program to obtain a descending key set view of a TreeMap using descendingKeySet() and print it.
• Write a Java program to convert a descending key set of a TreeMap into a list and then iterate over it.
• Write a Java program to iterate over the reverse order view of a TreeMap’s keys and print them with their indices.
• Write a Java program to compare the natural key set and the reverse key set of a TreeMap to validate the reverse ordering.

Java Code Editor:

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