Java Integer bitCount() method

The bitCount() method of Integer class of java.lang package returns the count of the number of one-bits in the two’s complement binary representation of an int value. This function is sometimes referred to as the population count. 

Syntax :

public static int bitCount(int n)
Parameter :
n : the value whose bits are to be counted
Return :
This method returns the count of the number of one-bits in the two's complement 
binary representation of an int value.

Example 01 : To show working of java.lang.Integer.bitCount() method. 

java

// Java program to demonstrate working
// of java.lang.Integer.bitCount() method

import java.lang.Integer;

class Gfg {
    // driver code
    public static void main(String args[])
    {
        int a = 10;

        // Convert integer number to binary  format
        System.out.println(Integer.toBinaryString(a));

        // to print number of 1's in the number a
        System.out.println(Integer.bitCount(a));
    }
}

Output

1010
2

Example 02 : To show working of bitCount() method. 

Java

import java.io.*;

class GFG {
    public static void main(String[] args)
    {
        int num1 = 10; // binary representation: 1010
        int num2 = -10; // binary representation:
                        // 11111111111111111111111111110110

        int result1 = Integer.bitCount(num1);
        int result2 = Integer.bitCount(num2);

        System.out.println("Number of one-bits in num1: "
                           + result1);
        System.out.println("Number of one-bits in num2: "
                           + result2);
    }
}

Output

Number of one-bits in num1: 2
Number of one-bits in num2: 30