java - Android 线程、锁、并发示例

Question

您好，我想知道在非 UI 线程的线程内的 while 循环中使用 Thread.sleep(x) 对性能有多糟糕...这不是使用 cpu 周期吗？例如

boolean[] flag = {false};    

//New thread to show some repeated animation
new Thread(new Runnnable{ run() {
    while(true){
        someImageView.animate()....setListener(.. onComplete(){ flag[0] = true; } ..).start();
    }

}).start()

//Wait for flag to be true to carry on in this thread
while(!flag[0]){
     Thread.sleep(100);
}

Answer 1

你应该使用一个synchronized block 来依赖wait/notify/notifyAll来同步你的线程，在你的情况下你甚至不需要修改任何状态，任何共享的 Object 实例就足够了。

代码可以是:

// Mutex to share between the threads waiting for the result.
Object mutex = new Object();
...
onComplete() { 
    synchronized (mutex) {
        // It is done so we notify the waiting threads
        mutex.notifyAll();
    }
}

synchronized (mutex) {
    // Wait until being notified
    mutex.wait();
}