Hashing Using Separate Chaining: Java Program

import java.util.Scanner;

class SLLNode

{

      int data;

      SLLNode next;

}

class SeparateChaining

{

      SLLNode htable[];

      int tableSize;

      public void insert(int key)

      {

            int index=key%tableSize;

            SLLNode newnode=new SLLNode() ;

            newnode.data=key;

            newnode.next=null;

            if(htable[index]==null)

                  htable[index]=newnode;

            else

            {

                  SLLNode c = htable[index];

                  while(c.next != null)

                        c=c.next;

                  c.next=newnode;

            }

      }

      public void display()

      {

            for(int i=0;i<tableSize;i++)

            {

                  SLLNode c=htable[i];

                  if(c == null)

                        System.out.println("no elements at index " + i);

                  else

                  {

                        System.out.print("elements at index "+i +" are  ");

                        while(c!=null)

                        {

                              System.out.print(c.data+"->");

                              c=c.next;

                        }

                        System.out.println();

                  }

            }

      }

      public void search(int key)

      {

            int index=key%tableSize;

            if(htable[index]==null)

                  System.out.println("element not found");

            else

            {

                  SLLNode c = htable[index];

                  while(c != null)

                  {

                        if(c.data == key)

                        {

            System.out.println("element found in linked list "+ index);

                              return;

                        }

                        c=c.next;

                  }

                  System.out.println("element not found");

            }

      }

}

public class SeparateChainingDemo

{

      public static void main(String[] args)

      {

            SeparateChaining ob=new SeparateChaining();

            Scanner sc=new Scanner(System.in);

            System.out.println("enter size of the table");

            ob.tableSize=sc.nextInt();

            ob.htable=new SLLNode[ob.tableSize];

            for(int i=0;i<ob.tableSize;i++)

                        ob.htable[i]=null;

            while(true)

            {

      System.out.println("press 1. insert 2. display 3. search 4. exit");

                  int choice=sc.nextInt();

                  switch(choice)

                  {

                  case 1:

                        System.out.println("enter key to be inserted");

                        int key=sc.nextInt();

                        ob.insert(key);

                        break;

                  case 2:

                        ob.display();

                        break;

                  case 3:

                        System.out.println("enter key to be searched");

                        key=sc.nextInt();

                        ob.search(key);

                        break;

                  default:

                        System.exit(0);

                  }

            }

      }

}

Output:
enter size of the table
10
press 1. insert 2. display 3. search 4. exit
1
enter key to be inserted
1
press 1. insert 2. display 3. search 4. exit
1
enter key to be inserted
11
press 1. insert 2. display 3. search 4. exit
1
enter key to be inserted
21
press 1. insert 2. display 3. search 4. exit
1
enter key to be inserted
31
press 1. insert 2. display 3. search 4. exit
2

no elements at index 0
elements at index 1 are 1->11->21->31->
no elements at index 2
no elements at index 3
no elements at index 4
no elements at index 5
no elements at index 6
no elements at index 7
no elements at index 8
no elements at index 9
press 1. insert 2. display 3. search 4. exit
3
enter key to be searched
1
element found in linked list 1
press 1. insert 2. display 3. search 4. exit
4

Algorithm to insert a value in hash table using separate chaining collision resolution technique

Hashtable is an array of pointers. All pointers are initialized to NULL  

Step1: Read the value to be inserted, key

step 2: create a new node using new operator

step 3: Assign the value read to the data field of newnode (newnode.data =key)

step 4: compute the index

                                        index = key % TABLE_SIZE

step 5: if head[ index] is NULL then

                                        step 5.1:  newnode becomes the only node in linked list or first node

step 6: else

                                        step 6.1 : attach the newnode at the end of linked list as lastnode