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Java BigInteger Class | bitLength() Method with Example

BigInteger Class bitLength() method: Here, we are going to learn about the bitLength() method of BigInteger Class with its syntax and example.
Submitted by Preeti Jain, on May 10, 2020

BigInteger Class bitLength() method

• bitLength() method is available in java.math package.
• bitLength() method is used to return the number of bits in minimum 2's complement denotation of this BigInteger without including a sign bit.
• bitLength() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• bitLength() method does not throw an exception at the time of counting bits.

Syntax:

    public int bitLength();

Parameter(s):

• None

Return value:

The return type of this method is int, it returns number of bits in minimum 2's complement denotation of this BigInteger with excluding a sign bit.

Example:

// Java program to demonstrate the example 
// of bitLength() method of BigInteger

import java.math.*;

public class BitLengthOfBI {
    public static void main(String args[]) {
        // Initialize two variables str1 and str2
        String str1 = "10";
        String str2 = "-4";

        // Initialize two BigInteger objects 
        BigInteger b_int1 = new BigInteger(str1);
        BigInteger b_int2 = new BigInteger(str2);

        System.out.println("b_int1: " + b_int1);
        System.out.println("b_int2: " + b_int2);

        // returns the number of bits in minimal 2's complement 
        // representation of this BigInteger b_dec1
        int bit_length = b_int1.bitLength();
        System.out.println("b_int1.bitLength(): " + bit_length);

        // returns the number of bits in minimal 2's complement 
        // representation of this BigInteger b_dec2 and it
        // does not differ from its sign bit
        bit_length = b_int2.bitLength();
        System.out.println("b_int2.bitLength(): " + bit_length);
    }
}

Output

b_int1: 10
b_int2: -4
b_int1.bitLength(): 4
b_int2.bitLength(): 2