Java HashMap clone()

Here, the shallow copy means the keys and values are not copied. Instead, references to keys/values are copied. To learn more about the shallow copy, visit Java Shallow Copy.

The syntax of the clone() method is:

hashmap.clone()

Here, hashmap is an object of the HashMap class.

clone() Parameters

The clone() method does not take any parameters.

clone() Return Value

• returns a copy of the HashMap instances (objects)

Example 1: Make a Copy of HashMap

Output

HashMap: {Java=14, JavaScript=1, Python=3}
Cloned HashMap: {Java=14, JavaScript=1, Python=3}

In the above example, we have created an hashmap named languages. Notice the expression,

(HashMap<String, Integer>)languages.clone()

Here,

• languages.clone() - returns a copy of the object languages
• (HashMap<String, Integer>) - converts object returned by clone() into a hashmap of String type key and Integer type values (To learn more, visit Java Typecasting)

Example 2: Print the Return Value of clone()

Output

Prime Numbers: {Five=5, Two=2, Three=3}
Return value of clone(): {Five=5, Two=2, Three=3}

In the above example, we have created an hashmap named primeNumbers. Here, we have printed the value returned by clone().

Note: The clone() method is not specific to the HashMap class. Any class that implements the Clonable interface can use the clone() method.