Java – Hashtable Example

Hashtable class is part of java.util package. Hashtable class can add key and value put(key, value) pair elements. Hashtable do not permit null key and value. But Hashtable is synchronized. Hashtable class return ordered entry as entered.
Hashtable extends Dictionary class and implements Map interface. Key and value of Hashtable can get by Set Interface and Map interface through Iterator and Enumeration interface.

Hashtable example give a method, how to use Hashtable in java

1. Hashtable example with Enumeration

import java.util.Hashtable;
import java.util.Enumeration;

public class HashTableExample {

    public static void main(String[] args) {

        Hashtable<Integer,String> hTable=new Hashtable<Integer,String>();

        //adding or set items in Hashtable by put method key and value pair
        hTable.put(new Integer(2), "Two");
        hTable.put(new Integer(1), "One");
        hTable.put(new Integer(4), "Four");
        hTable.put(new Integer(3), "Three");
        hTable.put(new Integer(5), "Five");

        // Get Hashtable Enumeration to get key and value
        Enumeration em=hTable.keys();

        while(em.hasMoreElements())
        {
            //nextElement is used to get key of Hashtable
            int key = (Integer)em.nextElement();

            //get is used to get value of key in Hashtable
            String value=(String)hTable.get(key);

            System.out.println("Key :"+key+"  value :"+value);
        }
    }
}

2. Hashtable example with Enumeration

import java.util.Hashtable;
import java.util.Iterator;
import java.util.Set;
import java.util.Map;

public class HashTableJava {

    public static void main(String[] args) {

        Hashtable<Integer,String> hTable=new Hashtable<Integer,String>();

        hTable.put(new Integer(2), "Two");
        hTable.put(new Integer(1), "One");
        hTable.put(new Integer(4), "Four");
        hTable.put(new Integer(3), "Three");
        hTable.put(new Integer(5), "Five");

        Set s =hTable.entrySet();

        Iterator i=s.iterator();

        while(i.hasNext())
        {
            Map.Entry m=(Map.Entry)i.next();

            int key = (Integer)m.getKey();
            String value=(String)m.getValue();

            System.out.println("Key :"+key+"  value :"+value);
        }
    }
}

Output

Key :5 value :Five
Key :4 value :Four
Key :3 value :Three
Key :2 value :Two
Key :1 value :One

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One Response to “Java – Hashtable Example”

  1. ashish says:
    July 23, 2010 at 5:40 pm

    Please correct the caption for second example.

    In place of “Hashtable example with Enumeration”
    “Hashtable example with Iterator” should be there.

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