Java Using Hashmap Program

How to iterate through HashMap

package com.java2novice.hashmap; 

import java.util.HashMap;

import java.util.Set;

public class MyHashMapRead

{

public static void main(String a[])

{

        HashMap hm = new HashMap();

        hm.put("first", "First inserted");

        hm.put("second", "Second inserted");

        hm.put("third","Third inserted");

        System.out.println(hm);

        Set keys = hm.keySet();

        for(String key: keys)

        {

            System.out.println("Value of "+key+" is: "+hm.get(key));

        }

    }

}

How to copy Map content to another HashMap

package com.java2novice.hashmap;

import java.util.HashMap;

public class MyHashMapCopy

{

public static void main(String a[])

{

        HashMap hm = new HashMap();

        hm.put("first", "First inserted");

        hm.put("second", "Second inserted");

        hm.put("third","Third inserted");

        System.out.println(hm);

        HashMap subMap = new HashMap();

        subMap.put("s1", "S1 Value");

        subMap.put("s2", "S2 Value");

        hm.putAll(subMap);

        System.out.println(hm);

    }

}

How to search a key in HashMap

package com.java2novice.hashmap;

import java.util.HashMap;

public class MyHashMapKeySearch

{

public static void main(String a[])

{

        HashMap hm = new HashMap();

        hm.put("first", "First inserted");

        hm.put("second", "Second inserted");

        hm.put("third","Third inserted");

        System.out.println(hm);

        if(hm.containsKey("first"))

        {

            System.out.println("The hashmap contains key first");

        }

        else

      {

            System.out.println("The hashmap does not contains key first");

        }

        if(hm.containsKey("fifth"))

        {

            System.out.println("The hashmap contains key fifth");

        }

        else

      {

            System.out.println("The hashmap does not contains key fifth");

        }

    }

}

How to search a value in HashMap

package com.java2novice.hashmap;

import java.util.HashMap;

public class MyHashMapValueSearch

{

public static void main(String a[])

{

        HashMap hm = new HashMap();

        hm.put("first", "First inserted");

        hm.put("second", "Second inserted");

        hm.put("third","Third inserted");

        System.out.println(hm);

        if(hm.containsValue("Second inserted"))

        {

            System.out.println("The hashmap contains value Second inserted");

        }

        else

      {

System.out.println("The hashmap does not contains value Second inserted");

        }

        if(hm.containsValue("first"))

        {

            System.out.println("The hashmap contains value first");

        }

        else

      {

            System.out.println("The hashmap does not contains value first");

        }

    }

}