java xor chemsum

checksum.java

import java.util.*;
import java.util.Random;
import java.util.Date;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

class Untitled {
	public static void main(String[] args) {
		int lim = 1000000;

		Set<String> returnList = new HashSet<>();

		char spaces[] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z'};
		Random ran = new Random();

		byte[] seq = new byte[10];
		char[] seqString = new char[10];
		String ss = "";
		Byte x = seq[0];
		int last = 0;

		// 算月份, 同一活動
		seq[0] = 'a';
		seq[1] = 'h';
		seq[2] = '3';
		seq[3] = 'y';
		seqString[0] = 'a';
		seqString[1] = 'h';
		seqString[2] = '3';
		seqString[3] = 'y';

		Date oo = new Date();
		int j=0;
		int ri = 0;
		// 跑一萬次
		while (returnList.size() <= lim) {
			// 跑 5 次隨機
			for(int i=0, ii=5; i< ii; i++){
				ri = ran.nextInt(spaces.length);
				seq[i+4] = (byte)spaces[ri];
				seqString[i+4] = spaces[ri];
			}

			x = seq[0];
			for(int i=0, ii=9; i<ii; i++){
				x= (byte)(x^seq[i]);
			}
			
			last = x.intValue() % (spaces.length);
			seqString[9]= spaces[last];

			// real String 
			ss = String.copyValueOf(seqString);
			returnList.add(ss);
			
			if(j%10000 ==0) {
				System.out.print(String.format("%012d, %s\n", j, ss));
			}
			j++;
		}
		System.out.print(String.format("%d 次\n",j));
//		String[] GPXFILES1 = returnList.toArray(new String[returnList.size()]);
//		for (int i = 0; i < lim; i++) {
//			System.out.print(String.format("%012d: %s\n", i, GPXFILES1[i]));
//		}
	}
}