不寻常的步数计数器读数

Question

I am trying to build a step counter app for android using the accerlerometer of the mobile. Without restarting the mobile, it gives almost accurate reading. That is for each steps, it increments the value by 1. When the mobile is restarted, the step counter value goes to 0 so i saved the value of the previous reading using the sharedPreferences . But when I start my mobile and start walking, for each steps the step counter increments by 2. How to solve it?

public class Pedometer extends Activity implements SensorEventListener {
    private TextView textView;

    private SensorManager mSensorManager;

    private Sensor mStepCounterSensor;

    private Sensor mStepDetectorSensor;

    SharedPreferences sharedPreferences;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pedometer);
        textView = (TextView) findViewById(R.id.textview);

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

    @Override
    public void onSensorChanged(SensorEvent event) {
        sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = sharedPreferences.edit();

        Sensor sensor = event.sensor;
        float[] values = event.values;
        int value = -1;
        if (values.length > 0) {
            value = (int) values[0];
        }

        int temp =  sharedPreferences.getInt("steps", 0);

        if (temp > value) {
            temp = temp + 1;
            editor.putInt("steps", temp).commit();
        } else {
            editor.putInt("steps", value).commit();
        }

        int count = sharedPreferences.getInt("steps", 0);

        if (sensor.getType() == Sensor.TYPE_STEP_COUNTER) {
            textView.setText("Step Counter Detected : " + count);
        } else if (sensor.getType() == Sensor.TYPE_STEP_DETECTOR) {
            // For test only. Only allowed value is 1.0 i.e. for step taken
            textView.setText("Step Detector Detected : " + count);
        }
    }

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

    }

    @Override
    protected void onResume() {

        super.onResume();

        mSensorManager.registerListener(this, mStepCounterSensor,

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

                SensorManager.SENSOR_DELAY_FASTEST);

    }

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

Answer 1

The problem is that your listener is not unregistered, just as some other people reported . Since you have multiple listeners registered and a shared variable, the steps will be counted twice. To solve this you will need to get a shared state to track if your listener is unregistered.