Java HashMap clear() Method Example

The clear() method of java.util.HashMap class will removes all of the mappings from this map. The map will be empty after this call returns.

Signature

public void clear()

This method removes all of the mappings from this map. The map will be empty after this call returns.

Example

The following example shows the usage of java.util.HashMap.clear() method.

import java.util.HashMap;
import java.util.Map;

public class ClearMethodTreeSetExample 
{
    public static void main(String args[])
    {
        // create an empty HashMap
        HashMap<Integer,String>  hashMap1 = new HashMap<Integer,String>();
        
        // use put() method to put elements to the HashMap
        hashMap1.put(1,"Element1");
        hashMap1.put(2,"Element2");
        hashMap1.put(3,"Element3");
        hashMap1.put(4,"Element4");
        hashMap1.put(5,"Element5");
        
        //printing the elements of the hashmap
        System.out.println("**Elements of the hashmap before clear**");
        for(Map.Entry<Integer,String> mapEntry : hashMap1.entrySet())
        {
            System.out.println("Key : "+mapEntry.getKey()+" Value : "+mapEntry.getValue());
        }
        
        //Clear the elements of the hashmap
        hashMap1.clear();
        
        //printing the elements of the hashmap
        System.out.println("**Elements of the hashmap after clear**");
        for(Map.Entry<Integer,String> mapEntry : hashMap1.entrySet())
        {
            System.out.println("Key : "+mapEntry.getKey()+" Value : "+mapEntry.getValue());
        }
    }
}

Output

**Elements of the hashmap before clear**
Key : 1 Value : Element1
Key : 2 Value : Element2
Key : 3 Value : Element3
Key : 4 Value : Element4
Key : 5 Value : Element5
**Elements of the hashmap after clear**

Leave a Reply

Your email address will not be published. Required fields are marked *