Question

我正在尝试为我的Android应用程序编写代码，当我按下按钮时，它将在后台运行一个功能，并在我再次按下按钮时退出。有人可以向我解释我是如何做到的。我知道这是围绕线程，但我只是无法弄明白。下面是代码。

    public void onMonitorClick(final View view){ //the button
    if (isBLEEnabled()) {
        if (!isDeviceConnected()) {
                // do nothing
        } else if (monitorvis == 0) {
            showMonitor(); //sets button to display "Stop" and sets monitorvis to 1;
            monitorStop = 1;

        } else if (monitorvis == 1) {
            hideMonitor(); //sets button to display "monitor" and sets monitorvis to 0;
            monitorStop = 0;
            run(); //this is the thread i want to run in the background, how do i 
                    //make it exit whenever i press onMonitorClick again?
        }
    } 
    else {
        showBLEDialog();
    }
}

protected void run() {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            ((ProximityService.ProximityBinder) getService()).getRssi();
            rssilevel = ((ProximityService.ProximityBinder) getService()).getRssiValue();
            mRSSI.setText(String.valueOf(rssilevel) + "dB");
            detectRange(rssilevel);
        }
    });
}

另外，如何使线程run（）延迟，因为它现在正在过快地轮询这些函数。请通过显示代码段或修改我的代码来解释。非常感谢你

现在尝试使用此代码，但没有成功

public void doWork() {  
ScheduledExecutorService service = Executors.newSingleThreadScheduledExecutor();
@SuppressWarnings("rawtypes")
ScheduledFuture future = service.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        ((ProximityService.ProximityBinder) getService()).getRssi();
        rssilevel = ((ProximityService.ProximityBinder) getService()).getRssiValue();
        mRSSI.setText(String.valueOf(rssilevel) + "dB");
        detectRange(rssilevel);
    }
}, 
0, // How long to delay the start
500, // How long between executions
TimeUnit.MILLISECONDS); // The time unit used

}

下次编辑帮助

    public void doWork() {
    if(mScheduleExecutorService == null) {
        mScheduleExecutorService = Executors.newSingleThreadScheduledExecutor();
    }
    if (mScheduleFuture == null) {
        mScheduleFuture = mScheduleExecutorService.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                    do {
                    ((ProximityService.ProximityBinder) getService()).getRssi();
                    rssilevel = ((ProximityService.ProximityBinder) getService()).getRssiValue();
                    mRSSI.setText(String.valueOf(rssilevel) + "dB");
                    detectRange(rssilevel); } while (monitorStop != 3);
                }
        }, 0, 500, TimeUnit.MILLISECONDS);
    }
}

Answer 1

在这种情况下我会使用ScheduledExecutor。周围有很多例子，但这里有一个快速剪辑：

ScheduleExecutorService service = Executors.newSingleThreadScheduledExecutor();
ScheduleFuture future = service.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
             // Perform your recurring method calls in here.
        }
    }
}, 
0, // How long to delay the start
500, // How long between executions
TimeUnit.MILLISECONDS); // The time unit used

确保在完成后关闭ExecutorService。因此，每当您的应用即将退出时（或者当他们第二次按下按钮时）：

service.shutdownNow(); // or service.shutdown();

对于上面的代码段，您需要以下导入：

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

看起来你很近并在路上。我会继续参考未来和服务，以便我可以在其他领域终止，关闭等。尝试以下方面：

private ScheduledExecutorService mScheduleExecutorService;
private ScheduledFuture mScheduleFuture;

public void onMonitorClick(final View view){ //the button
    if (isBLEEnabled()) {
        if (!isDeviceConnected()) {
                // do nothing
        } else if (monitorvis == 0) {
            showMonitor(); //sets button to display "Stop" and sets monitorvis to 1;
            monitorStop = 1;
            shutdownExecutor();
        } else if (monitorvis == 1) {
            hideMonitor(); //sets button to display "monitor" and sets monitorvis to 0;
            monitorStop = 0;
            doWork(); //this is the thread i want to run in the background, how do i 
                    //make it exit whenever i press onMonitorClick again?
        }
    } 
    else {
        showBLEDialog();
    }
}

public void doWork() {
    if(mScheduleExecutorService == null) {
        mScheduleExecutorService = Executors.newSingleThreadScheduledExecutor();
    }
    if (mScheduleFuture == null) {
        mScheduleFuture = mScheduleExecutorService.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                ((ProximityService.ProximityBinder) getService()).getRssi();
                rssilevel = ((ProximityService.ProximityBinder) getService()).getRssiValue();
                mRSSI.setText(String.valueOf(rssilevel) + "dB");
                detectRange(rssilevel);
            }
        }, 0, 500, TimeUnit.MILLISECONDS);
    }
}

private void shutdownExecutor() {
    if (mScheduleExecutorService != null && !mScheduleExecutorService.isShutdown()) {
        mScheduleExecutorService.shutdownNow();
    }
}

需要帮助在按钮按下后运行线程（Android应用程序）

1 个答案: