程序如下：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | public?static?void?main(String[]?args)?throws??Exception{ ????final?List?list?=?new?ArrayList(); ????final?Object?lock?=?new?Object(); ????Thread?t1?=?new?Thread(new?Runnable()?{ ????????@Override ????????public?void?run()?{ ????????????synchronized?(lock){ ????????????????for(int?i?=?0?;?i?<?10?;?i++){ ????????????????????list.add(i); ????????????????????if(list.size()?==?5){ ????????????????????????lock.notify(); ????????????????????????System.out.println(Thread.currentThread().getName()?+?"發出通知!"); ????????????????????} ????????????????} ????????????} ????????????System.out.println(Thread.currentThread().getName()?+?"execute?over!"); ????????} ????}); ????Thread?t2?=?new?Thread(new?Runnable()?{ ????????@Override ????????public?void?run()?{ ????????????synchronized?(lock){ ????????????????if(list.size()?!=?5){ ????????????????????try?{ ????????????????????????lock.wait(); ????????????????????}?catch?(InterruptedException?e)?{ ????????????????????????e.printStackTrace(); ????????????????????} ????????????????} ????????????????System.out.println(Thread.currentThread().getName()?+?"?收到通知!"); ????????????} ????????????System.out.println(Thread.currentThread().getName()?+?"execute?over!"); ????????} ????}); ????t2.start(); ????Thread.sleep(1000); ????t1.start(); } |
分析：
程序的意圖本是利用多線程之間的通信，利用wait/notify實現，可是運行的結果是雖然線程T1發出了通知，但是線程T2并沒有立即收到通知進行執行，這是為什么呢？?因為只有線程T1執行完畢釋放了鎖，T2才能執行，那么也就是說wait/notify并不是實時的（wait釋放了鎖，而notify沒有釋放鎖導致的），那么線程之間實時的通信該怎么做呢？可以利用CountDownLatch來實現。
對程序的改進：
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | public?static?void?main(String[]?args)?throws??Exception{ ????final?List?list?=?new?ArrayList(); ????final?Object?lock?=?new?Object(); ????final?CountDownLatch?countDownLatch?=?new?CountDownLatch(1); ????Thread?t1?=?new?Thread(new?Runnable()?{ ????????@Override ????????public?void?run()?{ ????????????????for(int?i?=?0?;?i?<?10?;?i++){ ????????????????????list.add(i); ????????????????????if(list.size()?==?5){ ????????????????????????countDownLatch.countDown(); ????????????????????????System.out.println(Thread.currentThread().getName()?+?"發出通知!"); ????????????????????} ????????????????} ????????????System.out.println(Thread.currentThread().getName()?+?"execute?over!"); ????????} ????}); ????Thread?t2?=?new?Thread(new?Runnable()?{ ????????@Override ????????public?void?run()?{ ????????????????if(list.size()?!=?5){ ????????????????????try?{ ????????????????????????countDownLatch.await(); ????????????????????}?catch?(InterruptedException?e)?{ ????????????????????????e.printStackTrace(); ????????????????????} ????????????????System.out.println(Thread.currentThread().getName()?+?"?收到通知!"); ????????????} ????????????System.out.println(Thread.currentThread().getName()?+?"execute?over!"); ????????} ????}); ????t2.start(); ????Thread.sleep(1000); ????t1.start(); } |
本文轉自zfz_linux_boy 51CTO博客，原文鏈接：http://blog.51cto.com/zhangfengzhe/1875221，如需轉載請自行聯系原作者
)
_【火眼金睛】超強解碼能力——邦納全新ABR系列讀碼器來襲！...)
方案)
![[arm驅動]linux內核時鐘](http://pic.xiahunao.cn/[arm驅動]linux內核時鐘)
