Java Program to Convert Binary Number to Decimal and vice-versa

In this program, you'll learn to convert binary number to a decimal number and vice-versa using functions in Java.

Visit this page to learn how to convert binary number to decimal.

Example 1: Program to convert binary number to decimal

public class BinaryDecimal {

    public static void main(String[] args) {
        long num = 110110111;
        int decimal = convertBinaryToDecimal(num);
        System.out.printf("%d in binary = %d in decimal", num, decimal);
    }

    public static int convertBinaryToDecimal(long num)
    {
        int decimalNumber = 0, i = 0;
        long remainder;
        while (num != 0)
        {
            remainder = num % 10;
            num /= 10;
            decimalNumber += remainder * Math.pow(2, i);
            ++i;
        }
        return decimalNumber;
    }
}

When you run the program, the output will be:

110110111 in binary = 439 in decimal

Visit this page to learn, how to convert decimal number to binary.

Example 2: Program to convert decimal number to binary

public class DecimalBinary {

    public static void main(String[] args) {
        int num = 19;
        long binary = convertDecimalToBinary(num);
        System.out.printf("%d in decimal = %d in binary", num, binary);
    }

    public static long convertDecimalToBinary(int n)
    {
        long binaryNumber = 0;
        int remainder, i = 1, step = 1;

        while (n!=0)
        {
            remainder = n % 2;
            System.out.printf("Step %d: %d/2, Remainder = %d, Quotient = %d\n", step++, n, remainder, n/2);
            n /= 2;
            binaryNumber += remainder * i;
            i *= 10;
        }
        return binaryNumber;
    }
}

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