Java Collection, HashMap Exercises: Get a shallow copy of a HashMap instance

Java Collection, HashMap Exercises: Exercise-6 with Solution

Write a Java program to get a shallow copy of a HashMap instance.

Sample Solution:-

Java Code:

import java.util.*;  
public class Example6 {  
   public static void main(String args[]){  
  HashMap<Integer,String> hash_map= new HashMap<Integer,String>();  
  hash_map.put(1, "Red");
  hash_map.put(2, "Green");
  hash_map.put(3, "Black");
  hash_map.put(4, "White");
  hash_map.put(5, "Blue");
    // print the map
   System.out.println("The Original map: " + hash_map);
   HashMap<Integer,String> new_hash_map= new HashMap<Integer,String>(); 
   new_hash_map = (HashMap)hash_map.clone();     
   System.out.println("Cloned map: " + new_hash_map);        

Sample Output:

Note: Example6.java uses unchecked or unsafe operations.               
Note: Recompile with -Xlint:unchecked for details.                     
The Original map: {1=Red, 2=Green, 3=Black, 4=White, 5=Blue}           
Cloned map: {1=Red, 2=Green, 3=Black, 4=White, 5=Blue}

Java Code Editor:

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Java: Tips of the Day


Converts to enum to Map where key is the name and value is Enum itself.

public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
    return Arrays.stream(enumClass.getEnumConstants())
            .collect(Collectors.toMap(Enum::name, Function.identity()));

Ref: https://bit.ly/3xXcFZt