Java lang.Long.builtcount() method in Java with Examples

java.lang.Long.bitCount() is a built in function in Java that returns the number of set bits in a binary representation of a number. It accepts a single mandatory parameter number whose number of set bits is returned.

Syntax:

public static long bitCount(long num)
Parameters:
num - the number passed 
Returns:
the number of set bits in the binary representation of the number 

Examples:

Input : 8 
Output : 1
Explanation: Binary representation : 1000 
No of set bits=1 

Input : 1032
Output : 2
Explanation: binary representation = 10000001000
no of set bits = 2

The program below illustrates the java.lang.Long.bitCount() function:

Program 1:

// Java program that demonstrates the use of
// Long.bitCount() function

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        long l = 1032;

        // prints the binary representation of the number
        System.out.println("binary representation = " + Long.toBinaryString(l));

        // prints the number of set bits
        System.out.println("no of set bits = " + Long.bitCount(l));
    }
}

Output:

 binary representation = 10000001000
no of set bits = 2

Program 2: When a negative number is passed in the argument

// Java program that demonstrates the use of
// Long.bitCount() function
// Negative number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        long l = -1032;

        // prints the binary representation of the number
        System.out.println("binary representation = " + Long.toBinaryString(l));

        // prints the number of set bits
        System.out.println("no of set bits = " + Long.bitCount(l));
    }
}

Output:

binary representation = 1111111111111111111111111111111111111111111111111111101111111000
no of set bits = 60 

Error: The function returns an error if any data-type other than long is passed as an argument.

Program 3: When decimal number is passed as an argument

// Java program that demonstrates the use of
// Long.bitCount() function
// decimal number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        // prints the number of set bits
        System.out.println("no of set bits = " + Long.bitCount(11.23));
    }
}

Output:

prog.java:15: error: incompatible types: possible lossy conversion from double to long
        System.out.println("no of set bits = " + Long.bitCount(11.23));

Program 4: When string number is passed as an argument

// Java program that demonstrates the use of
// Long.bitCount() function
// string number

// include lang package
import java.lang.*;

public class GFG {

    public static void main(String[] args)
    {

        // prints the number of set bits
        System.out.println("no of set bits = " + Long.bitCount("12"));
    }
}

Output:

prog.java:15: error: incompatible types: String cannot be converted to long
        System.out.println("no of set bits = " + Long.bitCount("12"));