Java Integer numberOfLeadingZeros() Method

The numberOfLeadingZeros() method is a method of Integer class under java.lang package. This method returns the total number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified integer value i.e. it converts int value to Binary then considers the highest one bit and returns total number of zero bits preceding it. In other words, if the specified integer value has no one-bits or is equal to zero in its two's complement representation then it will return 32.

Note: This method is closely related to the logarithm base 2. For all positive int values x:

floor(log2(x)) = 31 - numberOfLeadingZeros(x)
ceil(log2(x)) = 32 - numberOfLeadingZeros(x - 1).

Exaplanation:

Suppose, Integer Value = 55 
Binary Equivalent = 110111
Highest(Left-Most Bit) = 100000 i.e. at position 6
numberOfLeadingZeros = It will return in 32-bit representation, so preceding zero's are ( 32 - 6 = 26 ). 

Syntax:

Following is the declaration of numberOfLeadingZeros() method:

Parameter:

DataType	Parameter	Description	Required/Optional
int	i	It accepts integer value which returns highest order bit on its 2's complement.	Required

Returns:

The numberOfLeadingZeros() method returns the number of zero bits preceding the highest-order ("leftmost") one-bit in the two's complement binary representation of the specified integer value, or 32 if the value is equal to zero.

Exceptions:

Compatibility Version:

Java 1.5 and above

Example 1

public class IntegerNumberOfLeadingZerosExample1 {
	public static void main(String[] args) {
	System.out.println("Leading Zero's: "+Integer.numberOfLeadingZeros(10));       
    }
}

Output:

Leading Zero's: 28

Example 2

public class IntegerNumberOfLeadingZerosExample2 {
	public static void main(String[] args) {
		int value = 55;
		//Get the binary equivalent of this Integer value
		System.out.print("Binary equivalent: "+Integer.toBinaryString(value));
		//Print the number of Leading zeros
		System.out.print("\nNumber of Leading Zeros: "+Integer.numberOfLeadingZeros(value));
    }
}

Output:

Binary equivalent: 110111
Number of Leading Zeros: 26

Example 3

import java.util.Scanner;
public class IntegerNumberOfLeadingZerosExample3 {
	public static void main(String[] args) {
		//Get Numeric value from Console
		System.out.print("Enter the desired Integer value: ");
		Scanner readInput = new Scanner(System.in);
		int value = readInput.nextInt();
		readInput.close();
		//Get the binary equivalent of this Integer value
		System.out.print("Binary equivalent: "+Integer.toBinaryString(value));
		//Print the number of leading zeros
		System.out.print("\nNumber of Leading Zeros: "+Integer.numberOfLeadingZeros(value));
    }
}

Output:

Enter the desired Integer value: 75
Binary equivalent: 1001011
Number of Leading Zeros: 25

Example 4

public class IntegerNumberOfLeadingZerosExample4 {
	public static void main(String[] args) {
	  int num = -15;
        System.out.print("Input Number = " + num);
        // Returns the number of zero bits preceding the highest leftmost one-bit
        System.out.print("\nNumber of Leading Zeros = "+Integer.numberOfLeadingZeros(num));       
    }
}

Output:

Input Number = -15
Number of Leading Zeros = 0

Example 5

public class IntegerNumberOfLeadingZerosExample5 {
	public static void main(String[] args) {
	System.out.println("Leading Zero's: "+Integer.numberOfLeadingZeros(0));       
    }
}

Output: