Java Program to convert Decimal to Binary : Java Tutorial 3

Java program to 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-interger 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 Hindu-Arabic numeral system , decimal is the mostly used numeral system .

Binary :

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 :

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 Main {

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());

}
}
```