测试多线程中格式化日期列的安全问题

/**一个类中要访问多个线程，同时又用到格式化日期类时， 格式化日期类对象不能同时访问多个线程*访问多个线程，格式化日期类会出现意想不到的格式化错误，一个线程只能对应一个格式化日期类* author ：wuxq date：2011-10-26*/package biz;import java.text.SimpleDateFormat;import java.util.Date;public class Test {private SimpleDateFormat dateFormat;public static void main(String[] args) {SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");                SimpleDateFormat dateFormat2 = new SimpleDateFormat("yyyy-MM-dd");Date today = new Date();Date tomorrow = new Date(today.getTime() + 1000 * 60 * 60 * 24);System.out.println(today); // 今天是2011-10-27System.out.println(tomorrow); // 明天是2010-10-28synchronized (dateFormat) {Thread thread2 = new Thread(new Thread2(dateFormat, tomorrow));thread2.start();}synchronized (dateFormat2) {Thread thread1 = new Thread(new Thread1(dateFormat2, today));thread1.start();}}}class Thread1 implements Runnable {private SimpleDateFormat dateFormat;private Date date;public Thread1(SimpleDateFormat dateFormat, Date date) {this.dateFormat = dateFormat;this.date = date;}public void run() {for (;;) {// 一直循环到出问题为止吧。String strDate = dateFormat.format(date);System.out.println(strDate);// 如果不等于2010-01-11，证明出现线程安全问题了！！！！if (!"2011-10-27".equals(strDate)) {System.err.println("today=" + strDate);System.exit(0);}}}}class Thread2 implements Runnable {private SimpleDateFormat dateFormat;private Date date;public Thread2(SimpleDateFormat dateFormat, Date date) {this.dateFormat = dateFormat;this.date = date;}public void run() {for (;;) {String strDate = dateFormat.format(date);System.out.println(strDate);if (!"2011-10-28".equals(strDate)) {System.err.println("tomorrow=" + strDate);System.exit(0);}}}}

?