Open In App
Related Articles

HashMap clear() Method in Java

Improve
Improve
Improve
Like Article
Like
Save Article
Save
Report issue
Report
The java.util.HashMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified HashMap. Syntax:
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.HashMap.clear() Method: Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the clear() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<Integer, String> hash_map = new HashMap<Integer, String>();
  
        // Mapping string values to int keys
        hash_map.put(10, "Geeks");
        hash_map.put(15, "4");
        hash_map.put(20, "Geeks");
        hash_map.put(25, "Welcomes");
        hash_map.put(30, "You");
  
        // Displaying the HashMap
        System.out.println("Initial Mappings are: " + hash_map);
  
        // Clearing the hash map using clear()
        hash_map.clear();
  
        // Displaying the final HashMap
        System.out.println("Finally the maps look like this: " + hash_map);
    }
}

                    
Output:
Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
Finally the maps look like this: {}
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the clear() method
import java.util.*;
  
public class Hash_Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty HashMap
        HashMap<String, Integer> hash_map = new HashMap<String, Integer>();
  
        // Mapping int values to string keys
        hash_map.put("Geeks", 10);
        hash_map.put("4", 15);
        hash_map.put("Geeks", 20);
        hash_map.put("Welcomes", 25);
        hash_map.put("You", 30);
  
        // Displaying the HashMap
        System.out.println("Initial Mappings are: " + hash_map);
  
        // Clearing the hash map using clear()
        hash_map.clear();
  
        // Displaying the final HashMap
        System.out.println("Finally the maps look like this: " + hash_map);
    }
}

                    
Output:
Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25}
Finally the maps look like this: {}
Note: The same operation can be performed with any type of Mapping with variation and combination of different data types.

Last Updated : 26 Nov, 2018
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads