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HashMap clone() Method in Java

Last Updated : 06 Aug, 2025

The clone() method of the HashMap class in Java is used to create a shallow copy of the specified HashMap. The method returns a new HashMap that contains the same key-value mappings as the original HashMap.

Example 1: Here, we will use the clone() method to clone a HashMap of Integer keys and String values.

// Mapping String values to Integer keys
import java.util.HashMap;

public class GFG {
    public static void main(String[] args) {
      
        // Create a HashMap and add 
        // key-value pairs
        HashMap<Integer, String> hm = new HashMap<>();
        hm.put(1, "Java");
        hm.put(2, "C++");
        hm.put(3, "Python");

        // Print the original HashMap
        System.out.println("Original HashMap: " + hm);

        // Clone the HashMap
        HashMap<Integer, String> cl = 
          (HashMap<Integer, String>) hm.clone();

        // Print the cloned HashMap
        System.out.println("Cloned HashMap: " + cl);
    }
}

Original HashMap: {1=Java, 2=C++, 3=Python}
Cloned HashMap: {1=Java, 2=C++, 3=Python}

Explanation: In the above example, the clone() method creates a shallow copy of the HashMap. Both "hm" and "cl" contain the same key-value pairs.

To know more about Shallow copy and Deep copy refer this article: Shallow copy and Deep copy.

public Object clone()

• Parameters: The method does not take any parameters.
• Return Value: The clone() method returns a shallow copy of the HashMap.

Points to Remember:

• The clone is shallow means the keys and values themselves are not cloned, but references to them are copied.
• Changes to mutable objects inside the HashMap will reflect in both the original and the cloned HashMap.

Example 2: Here, we will use the clone() method to clone a HashMap of String keys and Integer values.

// Mapping Integer Values to String Keys 
import java.util.*;

public class GFG {
    public static void main(String[] args) {
      
        // Creating an empty HashMap
        HashMap<String, Integer> hm = new HashMap<String, Integer>();

        // Mapping string keys to integer values
        hm.put("Java", 1);
        hm.put("C++", 2);
        hm.put("Python", 3);

        // Print and display the HashMap
        System.out.println("Original HashMap: " + hm);

        // Clone the HashMap
        HashMap<String, Integer> cl 
          = (HashMap<String, Integer>) hm.clone();

        System.out.println("Cloned HashMap: " + cl);
    }
}

Original HashMap: {Java=1, C++=2, Python=3}
Cloned HashMap: {Java=1, C++=2, Python=3}

Important Points: 

• The same operation can be performed with any type of mappings with variation and combination of different data types.
• clone() method does the shallow copy. But here the values in the original and cloned hashmap will not affect each other because primitive data type is used.

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