Error Correction using Hamming Code (CN)

//Aim: Write a program for Error Correction using Hamming Code.
/*For complete explanation visit: Prof. Brinda's Blog*/

import java.util.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.*;
class HammingCode
{
   
    public static void main(String args[])
    {

    Scanner scr=new Scanner(System.in);
    System.out.println("This is hamming code error detection and correction using EVEN parity");
    System.out.println();
    System.out.println("Enter 4 data bits.D4 D3 D2 D1");
    int n=4;

    int d[]=new int[4]; //..........Array to accept data bits
    for(int i=n-1;i>=0;--i)
    {
    System.out.println("Enter the value of D"+(i+1));
    d[i]=scr.nextInt();
    }

    /*.............. Formula for calculating 2^k>=n+k+1 ...............*/

    int k=0;

    while(Math.pow(2,k)<(n+k+1))
    {
    ++k;
    }
    System.out.println();
    System.out.println(k+" parity bits are required for the transmission of data bits.");


    int p[]=new int[k]; //..........Array to store parity bits
    int h[]=new int[n+k+1];//.........Array to hold the hamming code.(n+k+1) as we start from pos 1.

    /********** Initializing array h[] to -1 ************/
    for(int i=0;i<7;++i)
    h[i]=-1;

    int count=0;
    int c=2;
    while(count<4)
    {
    ++c;
    if(c==4)
    continue;

    h[c]=d[count];
    ++count;
    }
    int p1[]={h[1],h[3],h[5],h[7]};
    int p2[]={h[2],h[3],h[6],h[7]};
    int p3[]={h[4],h[5],h[6],h[7]};
    int parity[]=new int[3];


    /************Setting the value of parity bit*************/
    parity[0]=set_parity_bit(p1);
    parity[1]=set_parity_bit(p2);
    parity[2]=set_parity_bit(p3);
   

    /************Inserting the parity bits in the hamming code**********/
    h[1]=parity[0];
    h[2]=parity[1];
    h[4]=parity[2];
   

    System.out.println("\nSENDER:");
    System.out.print("\nThe data bits entered are: ");
    for(int i=3;i>=0;--i)
    System.out.print(d[i]+" ");

    System.out.println("\nThe Parity bits are: ");
    for(int i=2;i>=0;--i)
    System.out.println("Value of P"+(i+1)+" is "+parity[i]+" ");

    System.out.print("\nThe Hamming code is as follows :-\nD4 D3 D2 P3 D1 P2 P1 \n");
    for(int i=(n+k);i>0;--i)
    System.out.print(h[i]+" ");

    System.out.println();
    System.out.println("\nEnter the hamming code with error at any position of your choice.");


    for(int i=7;i>0;--i)
    h[i]=scr.nextInt();

    int p4[]={h[1],h[3],h[5],h[7]};
    int p5[]={h[2],h[3],h[6],h[7]};
    int p6[]={h[4],h[5],h[6],h[7]};

    parity[0]=set_parity_bit(p4);
    parity[1]=set_parity_bit(p5);
    parity[2]=set_parity_bit(p6);

    int position=(int)(parity[2]*Math.pow(2,2)+parity[1]*Math.pow(2,1)+parity[0]*Math.pow(2,0));
    System.out.println("\nRECEIVER:");
    System.out.println("Error is detected at position "+position+" at the receiving end.");
    System.out.println("Correcting the error.... ");

    if(h[position]==1)
    h[position]=0;
    else
    h[position]=1;

    System.out.print("The correct code is ");
    for(int i=7;i>0;--i)
    System.out.print(h[i]+" ");
    }

   
    static int set_parity_bit(int a[])
    {
    int count=0;
    int l=a.length;

    for(int i=0;i<l;++i)
    if(a[i]==1)
    ++count;

    if((count%2)==0)
    return 0;
    else
    return 1;
    }

    }


OUTPUT

This is hamming code error detection and correction using EVEN parity

Enter 4 data bits.D4 D3 D2 D1
Enter the value of D4
1
Enter the value of D3
0
Enter the value of D2
1
Enter the value of D1
1

3 parity bits are required for the transmission of data bits.

SENDER:

The data bits entered are: 1 0 1 1
The Parity bits are:
Value of P3 is 0
Value of P2 is 0
Value of P1 is 1

The Hamming code is as follows :-
D4 D3 D2 P3 D1 P2 P1
1 0 1 0 1 0 1

Enter the hamming code with error at any position of your choice.
1
0
1
1
1
0
1

RECEIVER:
Error is detected at position 4 at the receiving end.
Correcting the error....
The correct code is 1 0 1 0 1 0 1