Java Integer bitCount() Method
Last Updated :
21 Jan, 2025
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The bitCount() method of Integer class of java.lang package returns the count of set bits in a positive number. For negative numbers, it returns the count of set bits in its 2s complement form. 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 set bits in a positive number. For negative numbers, it returns the count of set bits in its 2’s complement form.
Example 1: To show the working of java.lang.Integer.bitCount() method.
// 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
- Time Complexity: O(1), because the number of bits is fixed (32 bits for int).
- Auxiliary Space: O(1), as no extra space proportional to the input is used.
Example 2:
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
- Time Complexity: O(1), because the number of bits is fixed (32 bits for int).
- Auxiliary Space: O(1), as no extra space proportional to the input is used.
