WeakHashMap clear() Method in Java

The java.util.WeakHashMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified map.

Syntax:

Weak_Hash_Map.clear()

Parameters: The method does not accept any parameters.

Return Value: The method does not return any value.

Below programs are used to illustrate the working of java.util.WeakHashMap.clear() Method:



Program 1: Mapping String Values to Integer Keys.

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java code to illustrate the clear() method
import java.util.*;
  
public class Weak_Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty WeakHashMap
        Map<Integer, String> weak_hash = new WeakHashMap<Integer, String>();
  
        // Mapping string values to int keys
        weak_hash.put(10, "Geeks");
        weak_hash.put(15, "4");
        weak_hash.put(20, "Geeks");
        weak_hash.put(25, "Welcomes");
        weak_hash.put(30, "You");
  
        // Displaying the WeakHashMap
        System.out.println("Initial Mappings are: "
                           + weak_hash);
  
        // Clearing the map using clear()
        weak_hash.clear();
  
        // Displaying the final WeakHashMap
        System.out.println("Final Map: "
                           + weak_hash);
    }
}

chevron_right


Output:

Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
Final Map: {}

Program 2: Mapping Integer Values to String Keys.

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java code to illustrate the clear() method
import java.util.*;
  
public class Weak_Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty WeakHashMap
        Map<String, Integer> weak_hash = new WeakHashMap<String, Integer>();
  
        // Mapping int values to string keys
        weak_hash.put("Geeks", 10);
        weak_hash.put("4", 15);
        weak_hash.put("Geeks", 20);
        weak_hash.put("Welcomes", 25);
        weak_hash.put("You", 30);
  
        // Displaying the WeakHashMap
        System.out.println("Initial Mappings are: " + weak_hash);
  
        // Clearing the map using clear()
        weak_hash.clear();
  
        // Displaying the final WeakHashMap
        System.out.println("Final Map: "
                           + weak_hash);
    }
}

chevron_right


Output:

Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
Final Map: {}

Note: The same operation can be performed with any type of Mapping with variation and combination of different data types.

Attention reader! Don’t stop learning now. Get hold of all the important Java and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready.




My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.