Java Integer.bitCount() – Get number of bits in integer value

In this Java tutorial, you will learn about Integer.bitCount() method, and how to use this method to find the number of one-bits in specified integer, with the help of examples.

Integer.bitCount()

Integer.bitCount() returns the number of one-bits in the two’s complement binary representation of the specified int value.

Syntax

The syntax of bitCount() method is

Integer.bitCount(int i)

where

Parameter	Description
i	The integer value whose bits are to be counted.

Returns

The method returns value of type int.

Examples

1. Bit count of an integer

In this example, we will take an integer a and find the number of one-bits in the integer value using Integer.bitCount() method.

Java Program

public class Example{
	public static void main(String[] args){
		int a = 7;
		int count = Integer.bitCount(a);
		System.out.println("Bit count of " + a + " is: " + count);
	}
}

Output

Bit count of 7 is: 3

Explanation

7 = 00000111
Numbers of bits with value 1 is 3.

2. Bit count of multiple integers

In this example, we will find the one-bit count for multiple integers.

Java Program

public class Example{
	public static void main(String[] args){
		System.out.println("Bit count of 1 is: " + Integer.bitCount(1)); // 00000001
		System.out.println("Bit count of 2 is: " + Integer.bitCount(2)); // 00000010
		System.out.println("Bit count of 3 is: " + Integer.bitCount(3)); // 00000011
		System.out.println("Bit count of 4 is: " + Integer.bitCount(4)); // 00000100
		System.out.println("Bit count of 5 is: " + Integer.bitCount(5)); // 00000101
		System.out.println("Bit count of 6 is: " + Integer.bitCount(6)); // 00000110
		System.out.println("Bit count of 7 is: " + Integer.bitCount(7)); // 00000111
		System.out.println("Bit count of 8 is: " + Integer.bitCount(8)); // 00001000
		System.out.println("Bit count of 9 is: " + Integer.bitCount(9)); // 00001001
		System.out.println("Bit count of 10 is: " + Integer.bitCount(10)); // 00001010
	}
}

Output

Bit count of 1 is: 1
Bit count of 2 is: 1
Bit count of 3 is: 2
Bit count of 4 is: 1
Bit count of 5 is: 2
Bit count of 6 is: 2
Bit count of 7 is: 3
Bit count of 8 is: 1
Bit count of 9 is: 2
Bit count of 10 is: 2

Explanation

7 = 00000111
Numbers of bits with value 1 is 3.

Conclusion

In this Java Tutorial, we have learnt the syntax of Java Integer.bitCount() method, and also how to use this method with the help of Java example programs.