Question

使用Android Studio时我遇到线程问题。这是我的线程类：

class MainLoop extends Thread {


    private boolean run = true;

    @Override
    public void run() {
        System.out.println("Thread started");
        run = true;

        final double SPF = 1.0/2.0;
        double deltaS;
        long lastTime = System.nanoTime();
        long newTime;

        while(run) {
            newTime = System.nanoTime();
            deltaS = (float)(newTime-lastTime)/1000000000f;
            if (deltaS > SPF) {
                lastTime = newTime;
                System.out.println("Hello from thread");
            }
        }
        System.out.println("Thread killed");
    }

    void kill() {
        System.out.println("Killing thread");
        run = false;
    }

}

这是我的MainActivity类：

    public class MainActivity extends AppCompatActivity {


        private MainLoop mainLoop = null;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            mainLoop = new MainLoop();
            mainLoop.start();
        }

        @Override
        protected void onResume() {
            super.onResume();
            mainLoop = new MainLoop();
            mainLoop.start();
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            mainLoop.kill();
            return false;
        }
    }

这是我的输出：

08-15 12:24:07.480 2581-2667/com.lteii.hello I/System.out: Hello from thread
08-15 12:24:07.593 2581-2671/com.lteii.hello I/System.out: Hello from thread
08-15 12:24:07.595 2581-2581/com.lteii.hello D/ViewRootImpl@e1e91f8[MainActivity]: ViewPostImeInputStage processPointer 0
08-15 12:24:07.596 2581-2581/com.lteii.hello W/System: ClassLoader referenced unknown path: /system/framework/QPerformance.jar
08-15 12:24:07.597 2581-2581/com.lteii.hello E/BoostFramework: BoostFramework() : Exception_1 = java.lang.ClassNotFoundException: Didn't find class "com.qualcomm.qti.Performance" on path: DexPathList[[],nativeLibraryDirectories=[/system/lib, /vendor/lib]]
08-15 12:24:07.597 2581-2581/com.lteii.hello V/BoostFramework: BoostFramework() : mPerf = null
08-15 12:24:07.598 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.598 2581-2671/com.lteii.hello I/System.out: Thread killed
08-15 12:24:07.622 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.724 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.746 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.758 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.760 2581-2581/com.lteii.hello D/ViewRootImpl@e1e91f8[MainActivity]: ViewPostImeInputStage processPointer 1
08-15 12:24:07.760 2581-2581/com.lteii.hello I/System.out: Killing thread
08-15 12:24:07.980 2581-2667/com.lteii.hello I/System.out: Hello from thread
08-15 12:24:08.480 2581-2667/com.lteii.hello I/System.out: Hello from thread

我不明白它是怎么可能的，显然onResume（）方法每次用onTouchEvent（）方法杀死它都会重启线程，因为当我删除onResume（）时，我再也看不到了“Hello from线程“之后”线程被杀“ 无论如何，我应该在“Thread killed”和“Hello from thread”之间看到“Thread created” 我需要帮助！

Answer 1

尝试以下方法：

public class MainActivity extends AppCompatActivity {

    private MainLoop mainLoop = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (mainLoop == null) {
            mainLoop = new MainLoop();
            mainLoop.start();
        } else {
            System.out.println("onCreate: Thread has not been killed!");
        } 
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (mainLoop == null) {
            mainLoop = new MainLoop();
            mainLoop.start();
        } else {
            System.out.println("onResume: Thread has not been killed!");
        } 
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (mainLoop != null) {
            mainLoop.kill();
            mainLoop = null;
        } else {
            System.out.println("onTouchEvent: Thread has not been created!");
        }
        return false;
    }

这应该解释这个问题。一般的好习惯是仔细检查自己的代码。在最好的情况下，永远不会调用那些双重检查，在最坏的情况下，你知道为什么出现问题。

作为旁注：您创建的线程在无限循环中运行，因此无需任何操作即可快速耗尽电池电量。至少使用Thread.sleep或更好地使用ScheduledExecutor或Timer，如果您只有一个帖子。

线程似乎神奇地开始

1 个答案: