我有一个线程，试图获得用户的位置。
当接收到位置时，将调用“handler.sendMessage（msg）”，并返回true，但不会调用sendMessage。
logcat中没有错误或警告。
代码：

public class LocationThread extends Thread implements LocationListener {
    // ... Other (non-relevant) methods
    @Override
    public void run() {
        super.run();
        Looper.prepare();
        mainHandler = new Handler(Looper.myLooper()) {
            @Override
            public void handleMessage(Message msg) {
                // This method is never called
            }
        };
        locationManager.requestLocationUpdates(
                LocationManager.NETWORK_PROVIDER, 0, 0, this);
        Looper.loop();
    }
    @Override
    public void onLocationChanged(Location location) {
        // SendMessage is executed and returns true
        mainHandler.sendMessage(msg);
        if (mainHandler != null) {
            mainHandler.getLooper().quit();
        }
        locationManager.removeUpdates(this);
    }
}

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