Java BigInteger to bigIntegerToBytes(BigInteger integer)

Description

This function converts a big integer to its corresponding byte array format.

License

Open Source License

Parameter

Parameter	Description
integer	The big integer to be converted.

Return

The corresponding byte array.

Declaration

static public byte[] bigIntegerToBytes(BigInteger integer) 

Method Source Code

//package com.java2s;
/************************************************************************
 * Copyright (c) Crater Dog Technologies(TM).  All Rights Reserved.     *
 ************************************************************************
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.        *
 *                                                                      *
 * This code is free software; you can redistribute it and/or modify it *
 * under the terms of The MIT License (MIT), as published by the Open   *
 * Source Initiative. (See http://opensource.org/licenses/MIT)          *
 ************************************************************************/

import java.math.*;

public class Main {
    /**//from ww w  .j a  va 2s.  c  o m
     * This function converts a big integer to its corresponding byte array format.
     *
     * @param integer The big integer to be converted.
     * @return The corresponding byte array.
     */
    static public byte[] bigIntegerToBytes(BigInteger integer) {
        return integer.toByteArray();
    }

    /**
     * This function converts a big integer into its corresponding byte format and inserts
     * it into the specified buffer.
     *
     * @param integer The big integer to be converted.
     * @param buffer The byte array.
     * @return The number of bytes inserted.
     */
    static public int bigIntegerToBytes(BigInteger integer, byte[] buffer) {
        return bigIntegerToBytes(integer, buffer, 0);
    }

    /**
     * This function converts a big integer into its corresponding byte format and inserts
     * it into the specified buffer at the specified index.
     *
     * @param integer The big integer to be converted.
     * @param buffer The byte array.
     * @param index The index in the array to begin inserting bytes.
     * @return The number of bytes inserted.
     */
    static public int bigIntegerToBytes(BigInteger integer, byte[] buffer, int index) {
        int length = 4 + (integer.bitLength() + 8) / 8;
        System.arraycopy(intToBytes(length), 0, buffer, index, 4); // copy in the length
        index += 4;
        System.arraycopy(integer.toByteArray(), 0, buffer, index, length - 4); // copy in the big integer
        return length;
    }

    /**
     * This function converts a integer to its corresponding byte array format.
     *
     * @param i The integer to be converted.
     * @return The corresponding byte array.
     */
    static public byte[] intToBytes(int i) {
        byte[] buffer = new byte[4];
        intToBytes(i, buffer, 0);
        return buffer;
    }

    /**
     * This function converts a integer into its corresponding byte format and inserts
     * it into the specified buffer.
     *
     * @param i The integer to be converted.
     * @param buffer The byte array.
     * @return The number of bytes inserted.
     */
    static public int intToBytes(int i, byte[] buffer) {
        return intToBytes(i, buffer, 0);
    }

    /**
     * This function converts a integer into its corresponding byte format and inserts
     * it into the specified buffer at the specified index.
     *
     * @param i The integer to be converted.
     * @param buffer The byte array.
     * @param index The index in the array to begin inserting bytes.
     * @return The number of bytes inserted.
     */
    static public int intToBytes(int i, byte[] buffer, int index) {
        int length = buffer.length - index;
        if (length > 4)
            length = 4;
        for (int j = 0; j < length; j++) {
            buffer[index + length - j - 1] = (byte) (i >> (j * 8));
        }
        return length;
    }
}

Related

1. BigIntegerToByteArrayWithoutSign(BigInteger value)
2. bigIntegerToBytes(BigInteger b, int numBytes)
3. bigIntegerToBytes(BigInteger b, int numBytes)
4. bigIntegerToBytes(BigInteger b, int numBytes)
5. bigIntegerToBytes(BigInteger b, int numBytes)
6. bigIntegerToBytes(BigInteger n, byte[] data, int[] offset)
7. bigIntegerToBytes(final BigInteger bigInteger)
8. bigIntegerToDigits(BigInteger n)
9. BigIntegerToEightBytes(BigInteger value)