JAVA Program to Convert Decimal to Binary

In this tutorial, you will learn how to convert decimal to binary in JAVA using custom and toBinaryString() method and a custom method. 

Let us look at an example, 

• Decimal number: 23
• Binary number: 10111

• Decimal number: 19
• Binary number: 10011

Using Custom Method

Let us look at how to convert decimal to binary in JAVA using a custom method. 

Example:

//Java program to get the the binary notation of a decimal number

//Custom Method

//Importing the Scanner Class of Util Package
import java.util.Scanner;

//Main Class of the Program
public class Main
{
    //Main Method of the program
    public static void main(String[] args) {
        //Declaration of variables
        int numberModule,decimalNumber;
        String binaryNumber = "";
        //Creating the object of Scanner Class
        Scanner input = new Scanner(System.in);
        //Telling user what to enter
        System.out.print("Enter a Decimal Number : ");
        //Taking input from user
        decimalNumber = input.nextInt();
        //Loop till number is greater than 0
        while(decimalNumber > 0){
          //Finding the modulation of the entered number with 2
          numberModule = decimalNumber % 2;
          //Adding the modulation result in a variable
          binaryNumber = numberModule + "" + binaryNumber;
          //removing the last digit from entered number
          decimalNumber = decimalNumber / 2;
        }
        //Printing the result
        System.out.println("Binary Notation : "+binaryNumber);
    }
}

Output:

Enter a Decimal Number : 20
Binary Notation : 10100 

Using toBinaryString() method

The toBinaryString() method in Java returns the string representation of the integer argument that you pass to it. This string is unsigned integer in base 2. 

Example:

//Java program to get the the binary notation of a decimal number

//toBinaryString()

//Importing the Scanner Class of Util Package
import java.util.Scanner;

//Main Class of the Program
public class Main
{
    //Main Method of the program
    public static void main(String[] args) {
        //Declaration of variables
        int numberModule,decimalNumber;
        //Creating the object of Scanner Class
        Scanner input = new Scanner(System.in);
        //Telling user what to enter
        System.out.print("Enter a Decimal Number : ");
        //Taking input from user
        decimalNumber = input.nextInt();
        //Taking returned value from the toBinaryString Method in a variable
        String binaryNumber = Integer.toBinaryString(decimalNumber);
        //Printing the result
        System.out.println("Binary Notation : "+binaryNumber);
    }
}

Output:

Enter a Decimal Number : 21
Binary Notation : 10101 

Conclusion

Both the methods described above will help you convert a number from decimal to binary in Java. The custom function works fine, but the toBinaryString() method is faster and efficient.