Bitwise Addition, Decimal to Binary,Binary to Decimal, Add without using arithmetic operator, Add without Arithmetic

bitwise.java

// http://www.geeksforgeeks.org/add-two-numbers-without-using-arithmetic-operators/
// http://www.geeksforgeeks.org/add-two-bit-strings/
// Decimal to Binary
// http://www.geeksforgeeks.org/add-two-numbers-without-using-arithmetic-operators/
import java.lang.*;
class BitwiseAddition {
    
    public void add(String s1, String s2) {
     
        int l = s1.length();
        int sum;
        int c = 0;
        int c1, c2;
        
        StringBuilder result = new StringBuilder("");
        
        for(int i=l-1; i >=0; i--){
            
            c1 = s1.charAt(i) - '0'; // to convert char to int - 0
            c2 = s2.charAt(i) - '0';
            sum = c1 ^ c2 ^ c;    
            c = (c1 & c2) | ( c2 & c ) | ( c1 & c );
            result.append(sum);
        }
        if(c > 0)
            result.append(1);
        System.out.println(result.reverse());
    }

    public void DecimalToBinary(int n)
    {
        int r;
        StringBuilder result = new StringBuilder("");
        while(n>0)
        {
            r = n%2;
            result.insert(0, r);
            n = n/2;
        }
        System.out.println(result);
    }
    
    // add without using arithmetic operator
    public void add(int x, int y)
    {
        // Iterate till there is no carry  
        while (y != 0)
        {
            // carry now contains common set bits of x and y
            int carry = x & y;  
            // System.out.println(" Carry " + carry);
            
            // Sum of bits of x and y where at least one of the bits is not set
            x = x ^ y; 

            // Carry is shifted by one so that adding it to x gives the required sum
            y = carry << 1;
        }
        System.out.println(x);
    }
    
    public void addWithoutArithmetic(int x, int y)
    {
        int carry;
        // Iterate till there is no carry  
        while (y != 0)
        {
            // carry now contains common set bits of x and y
            carry = x & y;  

            // Sum of bits of x and y where at least one of the bits is not set
            x = x ^ y; 

            // Carry is shifted by one so that adding it to x gives the required sum
            y = carry << 1;
        }
        System.out.println(x);
    }
    
    public void decimalToBinary(int n)
    {
        
        int result = 0;
        int j = 0;
        int temp = 0;
        while(n>0)
        {
            temp = n % 10;
            result = result + temp * (int)(Math.pow(2, j));
            j++;
            n = n/10;
        }
        System.out.println(" Number: " + result);
    }
    
    public static void main(String args[]) {
        BitwiseAddition obj = new BitwiseAddition();
        // when length is not same do 0 padding to make length the same
        String s1 = "1100011";
        String s2 = "0000010";
        // obj.add(s1, s2);
        //obj.DecimalToBinary(10);
        //obj.add(10,40);
        //obj.addWithoutArithmetic(12,10);
        obj.decimalToBinary(1100);
    }
}