Java Program to convert Decimal to Binary in 3 ways

Java program to convert Decimal to Binary Number :

In this tutorial, we will check how to convert a decimal number to binary. We will use three different methods to convert one decimal number to its binary form.

Decimal :

For denoting integer and non-integer numbers, decimal number system uses 10 different digits, 0,1,2,3,4,5,6,7,8 and 9 i.e it is a base 10 number system. Also known as the Hindu-Arabic numeral system, decimal is the mostly used numeral system.

Binary :

The binary numeral system represents numeric values using 0 and 1. It is a base 2 system and each digit is known as ‘bit’.

Let’s take a look into the code :

Java program for Decimal to Binary conversion :

Method 1: Using an array of int :

In this method, we will use one array to store all reminders. And finally iterating through the array, we will print it out :

static void convertToBinary(int no){
    int[] container = new int[100];

    int i = 0;

    while (no > 0){
        container[i] = no%2;
        i++;
        no = no/2;
    }

    for (int j = i -1 ; j >= 0 ; j--){
        System.out.print(container[j]);
    }
}

Method 2: Using StringBuilder :

This method is similar to the previous one, but instead of using an array we will use one StringBuilder and append each reminder :

static void convertToBinaryUsingString(int no){
    StringBuilder result = new StringBuilder();

    int i =0;

    while (no > 0){
        result.append(no%2);
        i++;
        no = no/2;
    }
    System.out.println(result.reverse());

}

Method 3: Using inbuilt method public static String toBinaryString(int i) :

If you don’t want to find out the binary representation in one line, then “Integer” class has one static method known as toBinaryString(int). Use this method directly :

System.out.print(Integer.toBinaryString(no));

Full class :

import java.util.Scanner;

public class Example {

    public static void main(String[] args) {
        System.out.println("Please enter the number you want to convert : ");
        Scanner scanner = new Scanner(System.in);

        int no = scanner.nextInt();

        if (no > 0) {
            System.out.println("Binary conversion for " + no + " is :");

            System.out.println("Using Array :");
            convertToBinary(no);

            System.out.println("\nUsing StringBuilder :");
            convertToBinaryUsingString(no);

            System.out.println("\nUsing toBinaryString() :");
            System.out.print(Integer.toBinaryString(no));

        }

    }

    static void convertToBinary(int no) {
        int[] container = new int[100];

        int i = 0;

        while (no > 0) {
            container[i] = no % 2;
            i++;
            no = no / 2;
        }

        for (int j = i - 1; j >= 0; j--) {
            System.out.print(container[j]);
        }
    }

    static void convertToBinaryUsingString(int no) {
        StringBuilder result = new StringBuilder();

        int i = 0;

        while (no > 0) {
            result.append(no % 2);
            i++;
            no = no / 2;
        }
        System.out.println(result.reverse());

    }
}

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

Please enter the number you want to convert :
12
Binary conversion for 12is :
Using Array :
1100
Using StringBuilder :
1100

Using toBinaryString() :
1100

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