## Why is this an issue?

Optimizing resource usage and preventing unnecessary battery drain are critical considerations in Android development. Failing to release sensor resources when they are no longer needed can lead to prolonged device activity, negatively impacting battery life. Common Android sensors, such as cameras, GPS, and microphones, provide a method to release resources after they are not in use anymore.

This rule identifies situations where a sensor is not released after being utilized, helping developers maintain efficient and battery-friendly applications.

- Missing call to `release()` method:
  - `android.os.PowerManager.WakeLock`
  - `android.net.wifi.WifiManager$MulticastLock`
  - `android.hardware.Camera`
  - `android.media.MediaPlayer`
  - `android.media.MediaRecorder`
  - `android.media.SoundPool`
  - `android.media.audiofx.Visualizer`
  - `android.hardware.display.VirtualDisplay`
- Missing call to `close()` method
  - `android.hardware.camera2.CameraDevice`
- Missing call to `removeUpdates()` method:
  - `android.location.LocationManager`
- Missing call to `unregisterListener()` method:
  - `android.hardware.SensorManager`

## How to fix it

Ensure that resources are released when they are no longer needed. This can be done by calling the appropriate release method, such as `release()`, `removeUpdates()`, `unregisterListener()`, or `stop()`.

### Code examples

- `android.os.PowerManager.WakeLock`

#### Noncompliant code example

    public void method() {
      PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
      PowerManager.WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Wake Lock");
      wakeLock.acquire(); // Noncompliant
      // do some work...
    }

#### Compliant solution

    public void method() {
      PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
      PowerManager.WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Wake Lock");
      wakeLock.acquire(); // Compliant
      // do some work...
      wakeLock.release();
    }

- `android.media.MediaPlayer`

#### Noncompliant code example

    public void method() {
      MediaPlayer mediaPlayer = MediaPlayer.create(context, R.raw.sound_file_1);
      mediaPlayer.start(); // Noncompliant
      // do some work...
    }

#### Compliant solution

    public void onCreate() {
      MediaPlayer mediaPlayer = MediaPlayer.create(context, R.raw.sound_file_1);
      mediaPlayer.start(); // Compliant
      // do some work...
      wakeLock.release();
    }

- `android.hardware.SensorManager`

#### Noncompliant code example

    public void method() {
      SensorManager sensorManager = getSystemService(SENSOR_SERVICE);
      Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
      sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL); // Noncompliant
      // do some work...
    }

#### Compliant solution

    public void method() {
      SensorManager sensorManager = getSystemService(SENSOR_SERVICE);
      Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
      sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL); // Compliant
      // do some work...
      sensorManager.unregisterListener(this);
    }

## Resources

### Documentation

- Android - LocationManager
- Android - PowerManager.WakeLock
- Android - WifiManager.MulticastLock
- Android - MediaProjection
- Android - MediaPlayer
- Android - MediaRecorder
- Android - SoundPool
- Android - Visualizer
- Android - SensorManager
- Android - Keep the device awake
- Android - MediaPlayer Overview
- Android - Sensors Overview