Question

我尝试在Android中使用加速器，但在获取任何结果时遇到问题。

加速度计一直返回null，我不太确定事件监听器是否是问题，或其他什么。

我认为与此问题相关：

public class CalibrateScreen extends AppCompatActivity implements SensorEventListener{

    private SensorManager sensorMan;

    private float mAccel;
    private float mAccelCurrent;
    private float mAccelLast;
    boolean Calibration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_calibrate_screen);

        sensorMan = (SensorManager)getSystemService(SENSOR_SERVICE);
        Sensor accelerometer = sensorMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        sensorMan.registerListener(CalibrateScreen.this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);
        mAccel = 0.00f;
        mAccelCurrent = SensorManager.GRAVITY_EARTH;
        mAccelLast = SensorManager.GRAVITY_EARTH;
        Calibration = true;

    @Override
    public void onSensorChanged(SensorEvent sensorEvent) {
        if (sensorEvent.sensor.getType() == Sensor.TYPE_ACCELEROMETER){
            // Shake detection
            float x = sensorEvent.values[0];
            float y = sensorEvent.values[1];
            float z = sensorEvent.values[2];
            mAccelLast = mAccelCurrent;
            mAccelCurrent = (float) Math.sqrt(x*x + y*y + z*z);
            float delta = mAccelCurrent - mAccelLast;
            mAccel = mAccel * 0.9f + delta;
            //mAccel is the current acceleration.
            if (Calibration) {
                addMember(mAccel);
            }
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int i) {

    }

    @Override
    protected void onResume() {
        super.onResume();
        sensorMan.registerListener(this, sensorMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    protected void onStart() {
        super.onStart();
        sensorMan.registerListener(this, sensorMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    protected void onStop() {
        sensorMan.unregisterListener(this);
        super.onStop();
    }

}

完整代码pastebin在这里：https://pastebin.com/uREm9Esd

感谢您提前的时间

Answer 1

mAccelLast = mAccelCurrent;
mAccelCurrent = (float) Math.sqrt(x*x + y*y + z*z);
float delta = mAccelCurrent - mAccelLast;

问题出在第一行，它必须先进行delta计算; 有这样的错误，你没有null，你得到0值！

仅供参考：我听说加速度计有时它确实可以返回零点，但是没有看到这样的情况;

Accelerometer保持返回null

1 个答案: