BigInteger toByteArray() Method in Java (original) (raw)

Last Updated : 18 Apr, 2023

The java.math.BigInteger.toByteArray() method returns an array of bytes containing the two's-complement representation of this BigInteger. The most significant byte of the byte array is present in the zeroth element. The returning array from this method contains sign bit and the minimum number of bytes required to represent this BigInteger. The sign bit position is (ceil((this.bitLength() + 1)/8)).

Syntax:

public byte[] toByteArray()

Parameters: This method does not accept any parameters.

Return Value: This method returns a byte array containing the two's-complement representation of this BigInteger.

The below programs illustrate toByteArray() method of BigInteger class:

Example 1:

Java `

// Java program to demonstrate toByteArray() method of BigInteger

import java.math.BigInteger;

public class GFG {

public static void main(String[] args)
{

    // Creating BigInteger object
    BigInteger bigInt = BigInteger.valueOf(10);

    // create a byte array
    byte b1[];
    b1 = bigInt.toByteArray();

    // print result
    System.out.print("ByteArray of BigInteger "
                     + bigInt + " is");

    for (int i = 0; i < b1.length; i++) {
        System.out.format(" "
                              + "0x%02X",
                          b1[i]);
    }
}

}

`

Output:

ByteArray of BigInteger 10 is 0x0A

Example 2:

Java `

// Java program to demonstrate toByteArray() method of BigInteger

import java.math.BigInteger;

public class GFG {

public static void main(String[] args)
{

    // create byte array
    byte b[] = { 0x1, 0x2, 0x1 };

    // Creating BigInteger object using byte Array
    BigInteger bigInt = new BigInteger(b);

    // apply toByteArray() on BigInteger
    byte b1[] = bigInt.toByteArray();

    // print result
    System.out.print("ByteArray of BigInteger "
                     + bigInt + " is");

    for (int i = 0; i < b1.length; i++) {
        System.out.format(" "
                              + "0x%02X",
                          b1[i]);
    }
}

}

`