Hamming Code Generation for Error Detection and Correction > Java Program

Computer Networks

Hamming Code Generation for Error Detection and Correction > Java Program

import java.util.*;
class hamming
{
  public static void main(String args[]) 
    {


     Scanner scan = new Scanner(System.in);
     System.out.println("Enter the number of bits for the Hamming data:");
     int n = scan.nextInt();
     int a[] = new int[n];
     for(int i=0 ; i < n ; i++)
     {
      System.out.println("Enter bit no. " + (n-i) + ":");
      a[n-i-1] = scan.nextInt();
     }
    System.out.println("You entered:");
    for(int i=0 ; i < n ; i++)
    {
     System.out.print(a[n-i-1]);
    }
    System.out.println();
    int b[] = generateCode(a);
    System.out.println("Generated code is:");
    for(int i=0 ; i < b.length ; i++) {
    System.out.print(b[b.length-i-1]);
   }
   System.out.println();
   System.out.println("Enter position of a bit to alter to check for error detection at
   the receiver end (0 for no error):");
   int error = scan.nextInt();
   if(error != 0)
   {
    b[error-1] = (b[error-1]+1)%2;
    }
   System.out.println("Sent code is:");
   for(int i=0 ; i < b.length ; i++) {
   System.out.print(b[b.length-i-1]);
  }
  System.out.println();
  receive(b, b.length - a.length);
 }
static int[] generateCode(int a[])
{
 int b[];
 int i=0, parity_count=0 ,j=0, k=0;
 while(i < a.length)
 {
  if(Math.pow(2,parity_count) == i+parity_count + 1)
  {
   parity_count++;
  }
  else
 {
  i++;
 }
}
b = new int[a.length + parity_count];
for(i=1 ; i <= b.length ; i++)
{
 if(Math.pow(2, j) == i)
 {
  b[i-1] = 2;
  j++;
 }
 else
 {
  b[k+j] = a[k++];
 }
}
for(i=0 ; i < parity_count ; i++)
{
 b[((int) Math.pow(2, i))-1] = getParity(b, i);
}
return b;
}
static int getParity(int b[], int power) {
int parity = 0;
for(int i=0 ; i < b.length ; i++)
{
 if(b[i] != 2)
 {
  int k = i+1;
  String s = Integer.toBinaryString(k);
  int x = ((Integer.parseInt(s))/((int) Math.pow(10, power)))%10;
  if(x == 1)
 {
  if(b[i] == 1) 
  {
   parity = (parity+1)%2;
  }
 }
}
}
return parity;
}
static void receive(int a[], int parity_count) {
int power;
int parity[] = new int[parity_count];
String syndrome = new String();
for(power=0 ; power < parity_count ; power++)
{
 for(int i=0 ; i < a.length ; i++)
 {
  int k = i+1;
  String s = Integer.toBinaryString(k);
  int bit = ((Integer.parseInt(s))/((int) Math.pow(10, power)))%10;
  if(bit == 1)
  {
   if(a[i] == 1)
   {
    parity[power] = (parity[power]+1)%2;
   }
  }
 }
syndrome = parity[power] + syndrome;
}
int error_location = Integer.parseInt(syndrome, 2);
if(error_location != 0)
{
 System.out.println("Error is at location " + error_location + ".");
 a[error_location-1] = (a[error_location-1]+1)%2;
 System.out.println("Corrected code is:");
 for(int i=0 ; i < a.length ; i++)
 {
  System.out.print(a[a.length-i-1]);
 }
 System.out.println();
}
else
{
 System.out.println("There is no error in the received data.");
}
System.out.println("Original data sent was:");
power = parity_count-1;
for(int i=a.length ; i > 0 ; i--)
{
 if(Math.pow(2, power) != i)
 {
  System.out.print(a[i-1]);
 }
else
{
 power--;
}
}
System.out.println();
}
}