java – Define shaking

Question:

I am writing one application. I need to define the "shaking" of the device. How to implement this?

Answer:

1. Add an indication of the use of the sensor – accelerometer to the manifest

<uses-feature android:name="android.hardware.sensor.accelerometer" android:required="true" />

2. Create a class that implements the SensorEventListener interface in the SensorEventListener method onSensorChanged handle the sensor readings. For example like this:

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

public class ShakeDetector implements SensorEventListener {

    private static final float SHAKE_THRESHOLD_GRAVITY = 2.7F;
    private static final int SHAKE_SLOP_TIME_MS = 500;
    private static final int SHAKE_COUNT_RESET_TIME_MS = 3000;

    private OnShakeListener mListener;
    private long mShakeTimestamp;
    private int mShakeCount;

    public void setOnShakeListener(OnShakeListener listener) {
        this.mListener = listener;
    }

    public interface OnShakeListener {
        public void onShake(int count);
    }

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

    @Override
    public void onSensorChanged(SensorEvent event) {

        if (mListener != null) {
            float x = event.values[0];
            float y = event.values[1];
            float z = event.values[2];

            float gX = x / SensorManager.GRAVITY_EARTH;
            float gY = y / SensorManager.GRAVITY_EARTH;
            float gZ = z / SensorManager.GRAVITY_EARTH;

            float gForce = (float)Math.sqrt(gX * gX + gY * gY + gZ * gZ);

            if (gForce > SHAKE_THRESHOLD_GRAVITY) {
                final long now = System.currentTimeMillis();
                if (mShakeTimestamp + SHAKE_SLOP_TIME_MS > now) {
                    return;
                }

                if (mShakeTimestamp + SHAKE_COUNT_RESET_TIME_MS < now) {
                    mShakeCount = 0;
                }

                mShakeTimestamp = now;
                mShakeCount++;

                mListener.onShake(mShakeCount);
            }
        }
    }
}

3. Now you can use this class to show a dialogue in the activity after shaking the device. To do this, create an object of the SensorManager class, from it get an instance of the Sensor class, which, together with our implementation of SensorEventListener pass to the SensorManager#registerListener() method. Here is the activation code:

public class BaseActivity extends AppCompatActivity {

    private SensorManager mSensorManager;
    private Sensor mAccelerometer;
    private ShakeDetector mShakeDetector;
    private AlertDialog.Builder mDialogBuilder;
    private AlertDialog mAlertDialog;

    @Override
    public void onResume() {
        super.onResume();
        mSensorManager.registerListener(mShakeDetector, mAccelerometer, SensorManager.SENSOR_DELAY_UI);
    }

    @Override
    public void onPause() {
        mSensorManager.unregisterListener(mShakeDetector);
        super.onPause();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        mAccelerometer = mSensorManager
                .getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        mShakeDetector = new ShakeDetector();
        mShakeDetector.setOnShakeListener(new ShakeDetector.OnShakeListener() {

            @Override
            public void onShake(int count) {

                if (mAlertDialog == null || !mAlertDialog.isShowing()) {
                    mDialogBuilder = new AlertDialog.Builder(BaseActivity.this);
                    mDialogBuilder.setMessage("Ух-ты!")
                            .setCancelable(false)
                            .setNegativeButton(android.R.string.ok,
                                    new DialogInterface.OnClickListener() {
                                        public void onClick(DialogInterface dialog, int id) {
                                            dialog.cancel();
                                        }
                                    });
                    mAlertDialog = mDialogBuilder.create();
                    mAlertDialog.show();
                }
            }
        });
    }
}