Following Java program convert Decimal number to Binary number. Enter any integer as an input. Now we convert the given decimal input into a binary number with the help of String. We have taken a number in decimal and then done modulus division by 2, the remainder is added/concatenated to a binary number which is a String variable. The program output is also shown below.

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Decimal Number to Binary Number

In the program below, a number in Decimal format has been taken from the keyboard and passed to toBinary(int num) method. Where the number is converted by mode division by 2 and added to variable binaryNumber till the number becomes zero. And then return the value.

**Source Code:**

import java.io.*;

public class DecimalToBinary {

String binaryNumber; // Calculate the number into Binary as String

int rem; // Store the remainder as int

DecimalToBinary()

{

binaryNumber="";

rem=0;

}

// Binary Method

public String toBinary(int num)

{

if (num == 0)

{

return "0";

}

while (num > 0)

{

rem = num % 2;

binaryNumber = rem + binaryNumber;

num = num / 2;

}

return binaryNumber;

}

// Start main method

public static void main(String[] args) throws IOException

{

int decimal;

InputStreamReader in=new InputStreamReader(System.in);

BufferedReader br=new BufferedReader(in);

DecimalToBinary ob = new DecimalToBinary();

System.out.print("Enter a number to convert: ");

decimal=Integer.parseInt(br.readLine());

String bin = ob.toBinary(decimal); // Decimal to Binary method calling

System.out.println("The binary number representation is " + bin);

} // End of main method

}

__Output:__

Enter a number to convert: 100

The binary number representation is 1100100

Enter a number to convert: 15

The binary number representation is 1111

Enter a number to convert: 25

The binary number representation is 11001

We can convert **decimal to binary in java** using *Integer.toBinaryString()* method also

__Source Code:__

public class DecimalToBinaryWithMethod

{

public static void main(String args[])

{

Integer n1 = new Integer(100);

Integer n2 = new Integer(15);

Integer n3 = new Integer(25);

// Convertion using toBinaryString() method

String binary1 = Integer.toBinaryString(n1); // Method toBinaryString(n1)

String binary2 = Integer.toBinaryString(n2);

String binary3 = Integer.toBinaryString(n3);

System.out.println(binary1);

System.out.println(binary2);

System.out.println(binary3);

}

}

Output:

1100100

1111

11001

In the above program we have used Integer.toBinaryString() method to convert directly decimal number to binary number and store as String.

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