彻底搞懂Java多线程(四)

SimpleDateFormat非线程安全问题

实现1000个线程的时间格式化

1. package SimpleDateFormat;
2. import java.text.SimpleDateFormat;
3. import java.util.Date;
4. import java.util.concurrent.LinkedBlockingDeque;
5. import java.util.concurrent.ThreadPoolExecutor;
6. import java.util.concurrent.TimeUnit;
7. /**
8. * user：ypc；
9. * date：2021-06-13;
10. * time: 17:30;
11. */
12. public class SimpleDateFormat1 {
13. private static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("mm:ss");
14. public static void main(String[] args) {
15. ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(10,10,100,
16. TimeUnit.MILLISECONDS,new LinkedBlockingDeque<>(1000),new ThreadPoolExecutor.DiscardPolicy());
17.  
18. for (int i = 0; i < 1001; i++) {
19. int finalI = i;
20. threadPoolExecutor.submit(new Runnable() {
21. @Override
22. public void run() {
23. Date date = new Date(finalI * 1000);
24. myFormatTime(date);
25. }
26. });
27. }
28. threadPoolExecutor.shutdown();
29. }
30. private static void myFormatTime(Date date){
31. System.out.println(simpleDateFormat.format(date));
32. }
33. }

产生了线程不安全的问题