How to convert Java Decimal to Binary

In Java, Decimal value can be converted into Binary value either by using Integer.toBinaryString() method or own custom code. Let's see the examples.

1. Integer.toBinaryString() Method

The toBinaryString() method is a part of Integer class which converts the decimal into binary strings which further can be converted into other types like int or float.

Example 1:

Here, the decimal values are converted into binary strings by using the toBinaryString() method. See the example below.

public class StudyTonight
{    
	public static void main(String args[])
	{    
		int d1 = 7;
		int d2 = -232;
		int d3 = 90902;

		String b1 = Integer.toBinaryString(d1);
		String b2 = Integer.toBinaryString(d2);
		String b3 = Integer.toBinaryString(d3);

		System.out.println("Binary value is : " +b1);
		System.out.println("Binary value is : " +b2);
		System.out.println("Binary value is : " +b3);
	}    
}


Binary value is : 111
Binary value is : 11111111111111111111111100011000
Binary value is : 10110001100010110

Example 2:

The decimal values can be converted into binary using custom logic. This is the case when you don't want to use any built-in method.

public class StudyTonight
{    
	public static void main(String [] args)
	{  
		int dec = 343;
		int bin[] = new int[30];    
		int i = 0;    
		while(dec > 0)
		{    
			bin[i++] = dec%2;    
			dec = dec/2;    
		}    
		for(int j = i-1; j >= 0 ;j--)
		{    
			System.out.print(bin[j]);    
		}    
		System.out.println();
	}
}


101010111