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Hashtable in java


Hashtable:

Hashtable extends Dictionary class and implements Map interface. It contains elements in key-value pair. It not allowed duplicate key. It is synchronized. It can’t contain null key or value. It uses hashcode() method for finding the position of the elements.

Hashtable example:

HashtableTest.java

import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
 
/**
 * This class is used to show the Hashtable functionality.
 * @author codesjava
 */
public class HashtableTest {
	public static void main(String args[]){
		//Create Hashtable object.
		Hashtable hashtable = new Hashtable();
 
		//Add objects to the Hashtable.
		hashtable.put(2,"Bharat");
		hashtable.put(1,"Richi");
		hashtable.put(5,"Sahdev");
		hashtable.put(3,"Rajesh");
		hashtable.put(4,"Himanshu");
 
		//Print the Hashtable object.
		System.out.println("Hashtable elements:");
		System.out.println(hashtable);
 
		//Get iterator
		Set set=hashtable.entrySet();  
		Iterator iterator=set.iterator();  
 
		//Print the Hashtable elements using iterator.
		System.out.println("Hashtable elements using iterator:");
		while(iterator.hasNext()){
		   Map.Entry mapEntry=(Map.Entry)iterator.next();	
		   System.out.println("Key: " + mapEntry.getKey() + 
		       ", " + "Value: " + mapEntry.getValue());   
		}  
	}
}

Output:

Hashtable elements:
{5=Sahdev, 4=Himanshu, 3=Rajesh, 2=Bharat, 1=Richi}
Hashtable elements using iterator:
Key: 5, Value: Sahdev
Key: 4, Value: Himanshu
Key: 3, Value: Rajesh
Key: 2, Value: Bharat
Key: 1, Value: Richi

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