package com;
 
import java.nio.ByteBuffer;
import java.util.Arrays;
 
public class AAA {
    public static void main(String[] args) throws Exception {
        System.out.println("------------------> Test excessive data <-------------------");
        useCustomConvesion(345, 10);
        System.out.println("");
        useStandardConversion(345, 10);
        System.out.println("");
        System.out.println("------------------> Test overflow <-------------------");
        useCustomConvesion(345, 1);
        System.out.println("");
        useStandardConversion(345, 1);
    }
 
    private static void useCustomConvesion(int i, int arraySize) {
        byte[] b = intToByteArray(i, arraySize);
        System.out.println("Initial: " + i);
        System.out.println("As array: " + Arrays.toString(b));
        System.out.println("From array: " + byteArrayToInt(b, 0, b.length));
    }
 
    private static void useStandardConversion(int i, int arraySize) {
        byte[] b = ByteBuffer.allocate(arraySize).putInt(i).array();
        System.out.println("Initial: " + i);
        System.out.println("As array: " + Arrays.toString(b));
        System.out.println("From array: " + ByteBuffer.wrap(b).getInt()); 
    }
 
    private static int byteArrayToInt(byte[] b, int start, int length) {
        int dt = 0;
        if ((b[start] & 0x80) != 0)
            dt = Integer.MAX_VALUE;
        for (int i = 0; i < length; i++)
            dt = (dt << 8) + (b[start++] & 255);
        return dt;
    }
 
    private static byte[] intToByteArray(int n, int byteCount) {
        byte[] res = new byte[byteCount];
        for (int i = 0; i < byteCount; i++)
            res[byteCount - i - 1] = (byte) ((n >> i * 8) & 255);
        return res;
    }
}