Example 1: Program to convert binary number to decimal

1. public class BinaryDecimal {
3. public static void main(String[] args) {
4. long num = 110110111;
5. int decimal = convertBinaryToDecimal(num);
6. System.out.printf("%d in binary = %d in decimal", num, decimal);
7. }
9. public static int convertBinaryToDecimal(long num)
10. {
11. int decimalNumber = 0, i = 0;
12. long remainder;
13. while (num != 0)
14. {
15. remainder = num % 10;
16. num /= 10;
17. decimalNumber += remainder * Math.pow(2, i);
18. ++i;
19. }
20. return decimalNumber;
21. }
22. }

When you run the program, the output will be:

110110111 in binary = 439 in decimal

Example 2: Program to convert decimal number to binary

1. public class DecimalBinary {
3. public static void main(String[] args) {
4. int num = 19;
5. long binary = convertDecimalToBinary(num);
6. System.out.printf("%d in decimal = %d in binary", num, binary);
7. }
9. public static long convertDecimalToBinary(int n)
10. {
11. long binaryNumber = 0;
12. int remainder, i = 1, step = 1;
14. while (n!=0)
15. {
16. remainder = n % 2;
17. System.out.printf("Step %d: %d/2, Remainder = %d, Quotient = %d\n", step++, n, remainder, n/2);
18. n /= 2;
19. binaryNumber += remainder * i;
20. i *= 10;
21. }
22. return binaryNumber;
23. }
24. }

When you run the program, the output will be:

Step 1: 19/2, Remainder = 1, Quotient = 9
Step 2: 9/2, Remainder = 1, Quotient = 4
Step 3: 4/2, Remainder = 0, Quotient = 2
Step 4: 2/2, Remainder = 0, Quotient = 1
Step 5: 1/2, Remainder = 1, Quotient = 0
19 in decimal = 10011 in binary