Unsigned Multiplication Algorithm [Any number of bits]

import java.util.*;

public class UnsignedMultiplication {
    int[] decimalToBinary(int a, int n1) {
        int[] binary = new int[n1];
        int i = binary.length - 1;
        while (a != 0) {
            binary[i--] = a % 2;
            a /= 2;
        }
        return binary;
    }

    int[] add(int AQ[], int[] c) {
        int carry = 0;
        for (int i = c.length - 1; i >= 0; i--) {
            int temp = 0;
            temp = AQ[i] + c[i] + carry;
            AQ[i] = temp % 2;
            carry = temp / 2;
        }
        return AQ;
    }

    int[] shift(int AQ[]) {
        for (int i = AQ.length - 1; i >= 1; i--)
            AQ[i] = AQ[i - 1];
        AQ[0] = 0;
        return AQ;

    }

    void display(int[] AQ, int[] b, int[] c) {
        for (int i = 0; i < AQ.length; i++) {
            if (i == 1) {
                System.out.print("\t" + AQ[i]);
                continue;
            }
            if (i == c.length) {
                System.out.print("\t" + AQ[i]);
                continue;
            }
            System.out.print(AQ[i]);
        }
        System.out.print("\t");
        for (int i = 0; i < b.length; i++) {
            System.out.print(b[i]);
        }
    }

    void multiply(int a[], int b[], int c[]) {
        int AQ[] = new int[a.length + c.length];
        for (int i = 0; i < a.length; i++) {
            AQ[i + c.length] = a[i];
        }
        display(AQ, b, c);
        System.out.println();
        for (int i = 0; i < a.length; i++) {
            if (AQ[a.length + c.length - 1] == 1) {
                AQ = add(AQ, c);
                display(AQ, b, c);
                System.out.print("\t A+M\n");
            }
            shift(AQ);
            display(AQ, b, c);
            System.out.print("\t SHIFT \n");
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        UnsignedMultiplication u = new UnsignedMultiplication();
        System.out.println("Enter two numbers : ");
        int x = sc.nextInt();
        int y = sc.nextInt();
        int n = x > y ? x : y;
        int n1 = (int) (Math.log(n) / Math.log(2)) + 1;
        int a[] = u.decimalToBinary(x, n1);
        int b[] = u.decimalToBinary(y, n1);
        int c[] = u.decimalToBinary(y, n1 + 1);
        System.out.println("Q : " + Arrays.toString(a) + "\n" + "M : "
                + Arrays.toString(b));
        System.out.println("Carry\tA\tQ\tM");
        u.multiply(a, b, c);
    }

}


/*
OUTPUT :
Enter two numbers :
23
34
Q : [0, 1, 0, 1, 1, 1]
M : [1, 0, 0, 0, 1, 0]
Carry   A   Q   M
0   000000  010111  100010
0   100010  010111  100010   A+M
0   010001  001011  100010   SHIFT
0   110011  001011  100010   A+M
0   011001  100101  100010   SHIFT
0   111011  100101  100010   A+M
0   011101  110010  100010   SHIFT
0   001110  111001  100010   SHIFT
0   110000  111001  100010   A+M
0   011000  011100  100010   SHIFT
0   001100  001110  100010   SHIFT
*/