注冊傳感器偵聽器時，Android Wear應用程序崩潰

Question

我正在嘗試為Android Wear創建一個計步器應用程序。 我的問題是當我注冊傳感器偵聽器時

protected void onResume() {

    super.onResume();

    mSensorManager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_FASTEST);

}

應用程序崩潰，但是如果我刪除了該應用程序上方的代碼，但是詛咒傳感器偵聽器不起作用，那么如何使它起作用，這是代碼

public class WearMainActivity extends Activity implements SensorEventListener {

private SensorManager mSensorManager;
private Sensor mStepDetectorSensor;
TextView stepNum;
int steps = 12;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_wear_main);
    final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
    stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener() {
        @Override
        public void onLayoutInflated(WatchViewStub stub) {
            stepNum = (TextView) findViewById((R.id.stepNum));

            mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
            mStepDetectorSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_STEP_DETECTOR);




        }
    });






}

protected void onResume() {

    super.onResume();

    mSensorManager.registerListener(this, mStepDetectorSensor, SensorManager.SENSOR_DELAY_FASTEST);

}


@Override
public void onSensorChanged(SensorEvent event) {

    if (event.sensor.getType() == Sensor.TYPE_STEP_DETECTOR) {

        stepNum.setText(String.valueOf(steps));
    }

}


public void onAccuracyChanged(Sensor sensor, int accuracy) {

}


protected void onStop() {
    super.onStop();
    mSensorManager.unregisterListener(this,mStepDetectorSensor);
}

}

Answer 1

您應該在onResume方法中聲明這兩個變量：

protected void onResume() {
    super.onResume();
    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    mStepDetectorSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_STEP_DETECTOR);
    mSensorManager.registerListener(this, mStepDetectorSensor, SensorManager.SENSOR_DELAY_FASTEST);

}

並在onPause中注銷傳感器