HashMap clone() Method in Java

HashMap clear() Method in Java

Last Updated : 13 Dec, 2024

The clear() method of the HashMap class in Java is used to remove all of the elements or mappings (key-value pairs) from a specified HashMap.

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

Java

// Clearing HashMap of Integer keys 
// and String values
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(10, "Geeks");
        hm.put(15, "for");
        hm.put(20, "Geeks");
        hm.put(25, "Welcomes");
        hm.put(30, "You");

        // Print the initial HashMap
        System.out.println("Initial HashMap: " + hm);

        // Clear the HashMap
        hm.clear();

        // Print the HashMap after clearing
        System.out.println("After clear(): " + hm);
    }
}

Output

Initial HashMap: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=for}
After clear(): {}

Syntax of HashMap clear() Method

public void clear()

Parameters: This method does not accept any parameters.
Return Value: This method does not return any value.

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

Java

// Clearing HashMap of String keys 
// and Integer values
import java.util.HashMap;

public class GFG {
    public static void main(String[] args) {
      
        // Create a HashMap and add key-value pairs
        HashMap<String, Integer> hm = new HashMap<>();
        hm.put("Geeks", 10);
        hm.put("for", 15);
        hm.put("Geeks", 20); // Overwrites the previous value for "Geeks"
        hm.put("Welcomes", 25);
        hm.put("You", 30);

        // Print the initial HashMap
        System.out.println("Initial HashMap: " + hm);

        // Clear the HashMap
        hm.clear();

        // Print the HashMap after clearing
        System.out.println("After clear(): " + hm);
    }
}

Output

Initial HashMap: {Geeks=20, for=15, You=30, Welcomes=25}
After clear(): {}

Note: The HashMap will remain empty after invoking the clear() method, but the HashMap object still exists and can be reused.

HashMap clone() Method in Java

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