Implement Set using java

•  Implement Set using java

 HashSet

   It is used to create collection which uses hash table for storage of data and implements Set Interface.

 

Features

·                          It stores the elements by using mechanism called Hashing

·                          It contains unique elements only.

·                          It does not maintain insertion order  

Constructors

·                      HashSet()-initializes empty HashSet

·                      HashSet(Collection c)-constructs HashSet by using the elements of Collection

 Methods

·                   add(Object o)-adds the specified element to this set if it is not already present

·                   remove(Object o)-removes specified element from set

·                   clear()-removes all elements from the set

·                   size()-counts the number of elements in set

·                   iterator()- iterates over the elements in set

Program on HashSet

import java.util.Set;

import java.util.HashSet;

import java.util.Scanner;//Scanner class reads data from input stream

class Hashsetdemo

{

 public static void main(String[] args)

 {

  Set<Integer> obj=new HashSet<Integer>();//Set is interface and HashSet is class

  Scanner s=new Scanner(System.in);

  while(true)

  {

   System.out.println("1.Add");

   System.out.println("2.Remove");

   System.out.println("3.Display");

   System.out.println("4.Quit");

   System.out.println("Enter choice");

   int choice=s.nextInt();

   switch(choice)

   {

     case 1:System.out.println("Enter the element to be added to hashset");

            int e=s.nextInt();

            obj.add(e);//add element to hash set

            break;

     case 2:if(obj.isEmpty())//checks whether hashset is empty or not

            System.out.println("Hashset is empty");

            else

            {

            System.out.println("Enter the element to be removed from hashset");

            e=s.nextInt();

            if(obj.contains(e))//contains() checks whether hashset contains element or not

            { 

            obj.remove(e);

            System.out.println(e+" is removed from HashSet successfully");

            }

            else

            System.out.println("Element not found in hashset to be deleted");

            }

            break;

     case 3:if(obj.isEmpty())

             System.out.println("Hashset is empty");

            else

            {

            System.out.println("HashSet elements");

            for(Integer i:obj)//enhanced for loop

            System.out.println(i);

           //prints the elements using size()

          // convert hashset  to array

           // Integer[] i=obj.toArray(new Integer[obj.size()]);

            //for(int x=0;x<i.length;++x)

            //System.out.println(i[x]);

            // using Iterator interface to print all the elements in hashset

            //java.util.Iterator<Integer> y=obj.iterator();

            //while(y.hasNext())// checks whether hashset contains any more elements or not

            //System.out.println(y.next());//prints element

            }

            break;

     case 4:System.exit(0);

     default:System.out.println("Wrong choice");

    }

   }

  }

}

Expected Output

1.Add

2.Remove

3.Display

4.Quit

Enter choice

1

Enter the element to be added to hashset

10

1.Add

2.Remove

3.Display

4.Quit

Enter choice

1

Enter the element to be added to hashset

20

1.Add

2.Remove

3.Display

4.Quit

Enter choice

1

Enter the element to be added to hashset

30

1.Add

2.Remove

3.Display

4.Quit

Enter choice

1

Enter the element to be added to hashset

40

1.Add

2.Remove

3.Display

4.Quit

Enter choice

3

HashSet elements

20

40

10

30

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Enter the element to be removed from hashset

12

Element not found in hashset to be deleted

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Enter the element to be removed from hashset

40

40 is removed from HashSet successfully

1.Add

2.Remove

3.Display

4.Quit

Enter choice

3

HashSet elements

20

10

30

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Enter the element to be removed from hashset

30

30 is removed from HashSet successfully

1.Add

2.Remove

3.Display

4.Quit

Enter choice

3

HashSet elements

20

10

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Enter the element to be removed from hashset

10

10 is removed from HashSet successfully

1.Add

2.Remove

3.Display

4.Quit

Enter choice

3

HashSet elements

20

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Enter the element to be removed from hashset

20

20 is removed from HashSet successfully

1.Add

2.Remove

3.Display

4.Quit

Enter choice

2

Hashset is empty

1.Add

2.Remove

3.Display

4.Quit

Enter choice

3

Hashset is empty

1.Add

2.Remove

3.Display

4.Quit

Enter choice

4

------------------------------------------------------------------------------------------------------------------

LinkedHashSet

This class is used to create collection which extends HashSet class and implements Set interface.

Features
It stores the elements by using mechanism called Hashing
It contains unique elements only. 
It maintains insertion order
LinkedHashSet program

import java.util.Set;
import java.util.LinkedHashSet;
import java.util.Scanner;//Scanner class reads data from input stream
class Linkedhashsetdemo
{
 public static void main(String[] args)
 {
  Set<Integer> obj=new LinkedHashSet<Integer>();//Set is interface and LinkedHashSet is class
  Scanner s=new Scanner(System.in);
  while(true)
  {
   System.out.println("1.Add");
   System.out.println("2.Remove");
   System.out.println("3.Display");
   System.out.println("4.Quit");
   System.out.println("Enter choice");
   int choice=s.nextInt();
   switch(choice)
   {
     case 1:System.out.println("Enter the element to be added to linked hashset");
            int e=s.nextInt();
            obj.add(e);//add element to linked hash set
            break;
     case 2:if(obj.isEmpty())//checks whether linked hashset is empty or not
            System.out.println("Linked Hashset is empty");
            else
            {
            System.out.println("Enter the element to be removed from Linked hashset");
            e=s.nextInt();
            if(obj.contains(e))//contains() checks whether linkedhashset contains element or not
            { 
            obj.remove(e);
            System.out.println(e+" is removed from LinkedHashSet successfully");
            }
            else
            System.out.println("Element not found in linkedehashset to be deleted");
            }
            break;
     case 3:if(obj.isEmpty())
             System.out.println("LinkedHashset is empty");
            else
            {
            System.out.println("LinkedHashSet elements");
            for(Integer i:obj)//enhanced for loop
            System.out.println(i);
           //prints the elements using size()
          // convert hashset  to array
           // Integer[] i=obj.toArray(new Integer[obj.size()]);
            //for(int x=0;x<i.length;++x)
            //System.out.println(i[x]);
            // using Iterator interface to print all the elements in hashset
            //java.util.Iterator<Integer> y=obj.iterator();
            //while(y.hasNext())// checks whether hashset contains any more elements or not
            //System.out.println(y.next());//prints element
            }
            break;
     case 4:System.exit(0);
     default:System.out.println("Wrong choice");
    }
   }
  }
}

Expected Output
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to linked hashset
10
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to linked hashset
20
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to linked hashset
30
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to linked hashset
40
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to linked hashset
50
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
LinkedHashSet elements
10
20
30
40
50
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
30
30 is removed from LinkedHashSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
25
Element not found in linkedehashset to be deleted
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
LinkedHashSet elements
10
20
40
50
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
40
40 is removed from LinkedHashSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
10
10 is removed from LinkedHashSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
LinkedHashSet elements
20
50
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
20
20 is removed from LinkedHashSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from Linked hashset
50
50 is removed from LinkedHashSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Linked Hashset is empty
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
LinkedHashset is empty
1.Add
2.Remove
3.Display
4.Quit
Enter choice
4

TreeSet
It uses the tree for storage of elements which are maintained in increasing order.
Features
•	Contains unique elements
•	Fast retrieval and access of elements
•	Maintains ascending order
            Constructors
•	TreeSet()- constructs an empty TreeSet that will be sorted in an ascending order
•	TreeSet(Collection c)-constructs new TreeSet that contains the elements of collection
             Methods
•	add(Object o)-adds the specified element to this set if it is not already present
•	remove(Object o)-removes specified element from set
•	clear()-removes all elements from the set
•	size()-counts the number of elements in set
•	first()-returns the lowest element currently in this sorted set
•	last()-returns highest element currently in this sorted set
•	iterator()- iterates over the elements in set
TreeSet program
import java.util.Set;
import java.util.TreeSet;
import java.util.Scanner;//Scanner class reads data from input stream
class Treesetdemo
{
 public static void main(String[] args)
 {
  Set<Integer> obj=new TreeSet<Integer>();//Set is interface and TreeSet is class
  Scanner s=new Scanner(System.in);
  while(true)
  {
   System.out.println("1.Add");
   System.out.println("2.Remove");
   System.out.println("3.Display");
   System.out.println("4.Quit");
   System.out.println("Enter choice");
   int choice=s.nextInt();
   switch(choice)
   {
     case 1:System.out.println("Enter the element to be added to treeset");
            int e=s.nextInt();
            obj.add(e);//add element to tree set
            break;
     case 2:if(obj.isEmpty())//checks whether treeset is empty or not
            System.out.println("Hashset is empty");
            else
            {
            System.out.println("Enter the element to be removed from treeset");
            e=s.nextInt();
            if(obj.contains(e))//contains() checks whether treeset contains element or not
            { 
            obj.remove(e);
            System.out.println(e+" is removed from treeSet successfully");
            }
            else
            System.out.println("Element not found in treeset to be deleted");
            }
            break;
     case 3:if(obj.isEmpty())
             System.out.println("treeset is empty");
            else
            {
            System.out.println("TreeSet elements");
            for(Integer i:obj)//enhanced for loop
            System.out.println(i);
           //prints the elements using size()
          // convert hashset  to array
           // Integer[] i=obj.toArray(new Integer[obj.size()]);
            //for(int x=0;x<i.length;++x)
            //System.out.println(i[x]);
            // using Iterator interface to print all the elements in hashset
            //java.util.Iterator<Integer> y=obj.iterator();
            //while(y.hasNext())// checks whether hashset contains any more elements or not
            //System.out.println(y.next());//prints element
            }
            break;
     case 4:System.exit(0);
     default:System.out.println("Wrong choice");
    }
   }
  }
}

Expected Output
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to treeset
20
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to treeset
10
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to treeset
25
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to treeset
45
1.Add
2.Remove
3.Display
4.Quit
Enter choice
1
Enter the element to be added to treeset
42
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
TreeSet elements
10
20
25
42
45
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from treeset
25
25 is removed from treeSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
TreeSet elements
10
20
42
45
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from treeset
44
Element not found in treeset to be deleted
1.Add
2.Remove
3.Display
4.Quit
Enter choice
2
Enter the element to be removed from treeset
10
10 is removed from treeSet successfully
1.Add
2.Remove
3.Display
4.Quit
Enter choice
3
TreeSet elements
20
42
45
1.Add
2.Remove
3.Display
4.Quit
Enter choice

4