Java HashMap Pro

Remove value from Java Hash Map

import java.util.HashMap;

public class RemoveValueFromHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

Object obj = hMap.remove("2");

System.out.println(obj + " Removed from HashMap");

  }

}

Simple Java Hash Map

import java.util.HashMap;

public class JavaHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("One", new Integer(1));

hMap.put("Two", new Integer(2));

Object obj = hMap.get("One");

System.out.println(obj);  

   }

}

Check if a particular element exists in Java Hash Set

import java.util.HashSet; 

public class CheckElementHashSetExample

{

public static void main(String[] args)

{

HashSet hSet = new HashSet();

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

boolean blnExists = hSet.contains(new Integer("3"));

System.out.println("3 exists in HashSet ? : " + blnExists);

  }

}

Copy all elements of Java Hash Set to an Object Array

import java.util.HashSet; 

public class CopyElementsOfHashSetToArrayExample

{

public static void main(String[] args)

{

HashSet hSet = new HashSet();

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

Object[] objArray = hSet.toArray();

System.out.println("HashSet elements are copied into an Array.

Now Array Contains..");

for(int index=0; index < objArray.length ; index++)

System.out.println(objArray[index]);

   }

}

Get Size of Java Hash Set

import java.util.HashSet;  

public class GetSizeOfJavaHashSetExample

{

 public static void main(String[] args)

{

HashSet hSet = new HashSet();System.out.println("Size of HashSet : " + hSet.size());

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

System.out.println("Size of HashSet after addition : " + hSet.size());

hSet.remove(new Integer("1"));

System.out.println("Size of HashSet after removal : " + hSet.size());

   }

}

Iterate through elements of Java Hash Set

import java.util.HashSet;

import java.util.Iterator;

public class IterateThroughElementsOfHashSetExample

{

public static void main(String[] args)

{

HashSet hSet = new HashSet();

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

Iterator itr = hSet.iterator();

System.out.println("HashSet contains : ");

while(itr.hasNext())

System.out.println(itr.next());

   }

}

Remove all elements from Java Hash Set

import java.util.HashSet;

public class RemoveAllElementsFromHashSetExample

{

public static void main(String[] args)

{

HashSet hSet = new HashSet();

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

System.out.println("HashSet before removal : " + hSet);

hSet.clear();

System.out.println("HashSet after removal : " + hSet);

System.out.println("Is HashSet empty ? " + hSet.isEmpty());    

  }

}

Remove specified element from Java Hash Set

import java.util.HashSet;

public class RemoveSpecifiedElementFromHashSetExample

{

public static void main(String[] args)

{

HashSet hSet = new HashSet();

hSet.add(new Integer("1"));

hSet.add(new Integer("2"));

hSet.add(new Integer("3"));

System.out.println("HashSet before removal : " + hSet);

boolean blnRemoved = hSet.remove(new Integer("2"));

System.out.println("Was 2 removed from HashSet ? " + blnRemoved);

System.out.println("HashSet after removal : " + hSet);

  }

}