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Java BigInteger Class | toByteArray() Method with Example

BigInteger Class testBit() method: Here, we are going to learn about the testBit() method of BigInteger Class with its syntax and example.
Submitted by Preeti Jain, on May 12, 2020

BigInteger Class testBit() method

• testBit() method is available in java.math package.
• testBit() method is used to convert this BigInteger to a byte [] that holds 2's complement denotation of this BigInteger and the array capacity is enough to represent this BigInteger with one extra bit for the sign.
• testBit() 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.
• testBit() method does not throw an exception at the time of converting this object to a byte array.

Syntax:

    public byte[] toByteArray();

Parameter(s):

• None

Return value:

The return type of this method is byte[], it represents this BigInteger in terms of 2’s complement in byte array.

Example:

// Java program to demonstrate the example 
// of byte[] toByteArray() method of BigInteger

import java.math.*;
import java.util.*;

public class ToByteArrayOfBI {
    public static void main(String args[]) {
        // Initializes a variable str
        String str = "145";

        // Initializes a BigInteger object  
        BigInteger b_int = new BigInteger(str);

        // returns the convert this BigInteger 
        // into a byte[] that contains 2's complement of 
        // this BigInteger
        byte[] b_arr = b_int.toByteArray();
        for (int i = 0; i < b_arr.length; ++i)
            System.out.println("b_int.toByteArray(): " + b_arr[i] + " ");
    }
}

Output

b_int.toByteArray(): 0 
b_int.toByteArray(): -111