Hashset Array in Java Program

How to copy all elements from HashSet to an array

package com.java2novice.hashset;

import java.util.HashSet;

public class MyHashSetToArray

{

public static void main(String a[])

{

        HashSet hs = new HashSet();

        hs.add("first");

        hs.add("second");

        hs.add("third");

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

        System.out.println(hs);

        String[] strArr = new String[hs.size()];

        hs.toArray(strArr);

        System.out.println("Copied array content:");

        for(String str:strArr)

        {

            System.out.println(str);

        }

    }

}

How to compare two sets and retain elements which are same on both sets

package com.java2novice.hashset;

import java.util.HashSet;

public class MyHashSetRetain

{

public static void main(String a[])

    {

        HashSet hs = new HashSet();

        hs.add("first");

        hs.add("second");

        hs.add("third");

        hs.add("apple");

        hs.add("rat");

        System.out.println(hs);

        HashSet subSet = new HashSet();

        subSet.add("rat");

        subSet.add("second");

        subSet.add("first");

        hs.retainAll(subSet);

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

        System.out.println(hs);

    }

}

How to eliminate duplicate user defined objects from HashSet

package com.java2novice.hashset;

import java.util.HashSet;

public class MyDistElementEx

{

public static void main(String a[])

{

        HashSet lhm = new HashSet();

        lhm.add(new Price("Banana", 20));

        lhm.add(new Price("Apple", 40));

        lhm.add(new Price("Orange", 30));

        for(Price pr:lhm)

       {

            System.out.println(pr);

        }

        Price duplicate = new Price("Banana", 20);

        System.out.println("inserting duplicate object...");

        lhm.add(duplicate);

        System.out.println("After insertion:");

        for(Price pr:lhm)

        {

            System.out.println(pr);

        }

    }

}

class Price

 {

    private String item;

    private int price; 

public Price(String itm, int pr)

    {

        this.item = itm;

        this.price = pr;

    }     

 public int hashCode()

   {

        System.out.println("In hashcode");

        int hashcode = 0;

        hashcode = price*20;

        hashcode += item.hashCode();

        return hashcode;

    }

public boolean equals(Object obj)

 {

        System.out.println("In equals");

        if (obj instanceof Price)

       {

            Price pp = (Price) obj;

            return (pp.item.equals(this.item) && pp.price == this.price);

        }

         else

        {

            return false;

        }

    }

public String getItem()

  {

        return item;

    }

 public void setItem(String item)

{

        this.item = item;

    }

 public int getPrice()

{

        return price;

    }

 public void setPrice(int price)

 {

        this.price = price;

    }

  public String toString()

 {

        return "item: "+item+"  price: "+price;

    }

}

How to find user defined objects from HashSet

package com.java2novice.hashset;

import java.util.HashSet;

public class MyHashSetSearchObject

{

 public static void main(String a[])

{

        HashSet lhs = new HashSet();

        lhs.add(new Price("Banana", 20));

        lhs.add(new Price("Apple", 40));

        lhs.add(new Price("Orange", 30));

        for(Price pr:lhs)

        {

            System.out.println(pr);

        }

        Price key = new Price("Banana", 20);

        System.out.println("Does set contains key? "+lhs.contains(key));

    }

}

class Price

{ 

    private String item;

    private int price;

  public Price(String itm, int pr)

 {

        this.item = itm;

        this.price = pr;

    }

public int hashCode()

  {

        System.out.println("In hashcode");

        int hashcode = 0;

        hashcode = price*20;

        hashcode += item.hashCode();

        return hashcode;

    }

 public boolean equals(Object obj)

 {

        System.out.println("In equals");

        if (obj instanceof Price)

        {

            Price pp = (Price) obj;

            return (pp.item.equals(this.item) && pp.price == this.price);

        }

        else

       {

            return false;

        }

    }

    public String getItem()

   {

        return item;

    }

    public void setItem(String item)

   {

        this.item = item;

    }

    public int getPrice()

    {

        return price;

    }

    public void setPrice(int price)

    {

        this.price = price;

    }

    public String toString()

   {

        return "item: "+item+"  price: "+price;

    }

}