Java program to convert a decimal to binary format for a float or double value

Java program to convert a decimal to binary format for a float or double value:

In this post, we will write one Java program that will convert one decimal value to binary format. The value will be a floating point variable or double variable, i.e. it will have both integral and fractional parts.

For example, for the number 1.23, 1 is the integral part and .23 is the fractional part.

If we are converting 1.23 to binary, we have to convert both 1 and .23.

How to convert floating numbers to binary numbers:

To convert a floating number to binary, we have to convert both integral and fractional parts.

Convert the integral part to binary:

Follow the below steps to convert the integral part to binary:

Find the remainder if we divide the number by 2. Save it in an array.
Divide the number by 2 and set this value as the new value for the number.
Repeat it until the number is greater than 2.
Once done, print all remainders in reverse order.

Convert the fractional part to binary:

Follow the below steps to convert the fractional part to binary:

Multiply the fractional part by 2. Save the value before the decimal point.
Set the fractional part of the new number and set it as the new number.
Repeat these steps until it becomes 1.0.
Print these values in the same order.

Let me show you with an example:

For the number 4.25, we need to find the binary for 4 and .25.

4 to binary:

[current value]	[remainder for divide by 2]	[quotient for divide by 2]
4	0	2
2	0	1
1	1	0

If we take the remainders in reverse order, it will give us the binary for 4: 100

.25 to binary

[current value]	[multiply by 2]	[value before decimal]
.25	0.5	0
.5	1.0	1
0	stop	stop

So, the binary for .25 is 01

Now, if we combine the binary results of 4 and .25, it will give us the binary for 4.25 i.e. 100.01 is the binary for 4.25

Java Program:

Let’s write it down in a Java program:

import java.util.Scanner;

class MyClass {
    private static String findBinary(double num) {
        StringBuilder binaryBuilder = new StringBuilder();
        int numIntegral = (int) num;
        double numFractional = num - numIntegral;

        // binary conversion for the integral part
        while (numIntegral > 0) {
            binaryBuilder.append(numIntegral % 2);
            numIntegral /= 2;
        }

        binaryBuilder.reverse();

        // binary conversion for the fractional part
        if (numFractional != 0) {
            binaryBuilder.append(".");

            while (numFractional != 0) {
                numFractional *= 2;
                binaryBuilder.append((int) numFractional);
                numFractional = numFractional - (int) numFractional;
            }
        }

        return binaryBuilder.toString();
    }

    public static void main(String[] args) {
        double num;
        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a number: ");
        num = sc.nextDouble();

        System.out.println("Binary: " + findBinary(num));
    }

}

In this program,

findBinary method is used to convert a double to binary.
This method breaks the double number to an integral and fractional parts and finds the binary values for each.
It uses a StringBuilder and appends the binary value to this builder.
First, it uses a while loop to find the binary of the integral part and appends that to the builder. Then it reverse the result.
Next, it checks if there is any fractional value available or not. If yes, it appends a . and finds the binary for the fractional part, appends to the builder.
Finally, it converts the StringBuilder to a string and returns that result.

Sample output:

If you run this program, it will print output as like below:

Enter a number: 
222.5
Binary: 11011110.1

Enter a number: 
222
Binary: 11011110

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Java program to convert a decimal to binary format for a float or double value