178168cc72
Co-authored-by: Irina Batinic <irina.batinic@sonarsource.com> Co-authored-by: Angelo Buono <angelo.buono@sonarsource.com>
130 lines
4.7 KiB
Plaintext
130 lines
4.7 KiB
Plaintext
== Why is this an issue?
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Optimizing resource usage and preventing unnecessary battery drain are critical considerations in Android development.
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Failing to release sensor resources when they are no longer needed can lead to prolonged device activity, negatively impacting battery life.
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Common Android sensors, such as cameras, GPS, and microphones, provide a method to release resources after they are not in use anymore.
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This rule identifies situations where a sensor is not released after being utilized, helping developers maintain efficient and battery-friendly applications.
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* Missing call to `release()` method:
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- `android.os.PowerManager.WakeLock`
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- `android.net.wifi.WifiManager$MulticastLock`
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- `android.hardware.Camera`
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- `android.media.MediaPlayer`
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- `android.media.MediaRecorder`
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- `android.media.SoundPool`
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- `android.media.audiofx.Visualizer`
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- `android.hardware.display.VirtualDisplay`
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* Missing call to `close()` method
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- `android.hardware.camera2.CameraDevice`
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* Missing call to `removeUpdates()` method:
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- `android.location.LocationManager`
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* Missing call to `unregisterListener()` method:
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- `android.hardware.SensorManager`
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== How to fix it
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Ensure that resources are released when they are no longer needed.
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This can be done by calling the appropriate release method, such as `release()`, `removeUpdates()`, `unregisterListener()`, or `stop()`.
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=== Code examples
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* `android.os.PowerManager.WakeLock`
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==== Noncompliant code example
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[source,java,diff-id=1,diff-type=noncompliant]
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----
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public void method() {
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PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
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PowerManager.WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Wake Lock");
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wakeLock.acquire(); // Noncompliant
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// do some work...
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}
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----
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==== Compliant solution
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[source,java,diff-id=1,diff-type=compliant]
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----
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public void method() {
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PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
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PowerManager.WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Wake Lock");
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wakeLock.acquire(); // Compliant
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// do some work...
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wakeLock.release();
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}
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----
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* `android.media.MediaPlayer`
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==== Noncompliant code example
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[source,java,diff-id=2,diff-type=noncompliant]
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----
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public void method() {
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MediaPlayer mediaPlayer = MediaPlayer.create(context, R.raw.sound_file_1);
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mediaPlayer.start(); // Noncompliant
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// do some work...
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}
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----
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==== Compliant solution
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[source,java,diff-id=2,diff-type=compliant]
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----
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public void onCreate() {
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MediaPlayer mediaPlayer = MediaPlayer.create(context, R.raw.sound_file_1);
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mediaPlayer.start(); // Compliant
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// do some work...
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wakeLock.release();
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}
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----
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* `android.hardware.SensorManager`
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==== Noncompliant code example
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[source,java,diff-id=3,diff-type=noncompliant]
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----
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public void method() {
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SensorManager sensorManager = getSystemService(SENSOR_SERVICE);
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Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
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sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL); // Noncompliant
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// do some work...
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}
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----
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==== Compliant solution
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[source,java,diff-id=3,diff-type=compliant]
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----
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public void method() {
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SensorManager sensorManager = getSystemService(SENSOR_SERVICE);
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Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
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sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL); // Compliant
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// do some work...
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sensorManager.unregisterListener(this);
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}
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----
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== Resources
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=== Documentation
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* https://developer.android.com/reference/android/location/LocationManager[Android - LocationManager]
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* https://developer.android.com/reference/android/os/PowerManager.WakeLock[Android - PowerManager.WakeLock]
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* https://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock[Android - WifiManager.MulticastLock]
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* https://developer.android.com/reference/android/media/projection/MediaProjection[Android - MediaProjection]
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* https://developer.android.com/reference/android/media/MediaPlayer[Android - MediaPlayer]
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* https://developer.android.com/reference/android/media/MediaRecorder[Android - MediaRecorder]
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* https://developer.android.com/reference/android/media/SoundPool[Android - SoundPool]
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* https://developer.android.com/reference/android/media/audiofx/Visualizer[Android - Visualizer]
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* https://developer.android.com/reference/android/hardware/SensorManager[Android - SensorManager]
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* https://developer.android.com/develop/background-work/background-tasks/scheduling/wakelock[Android - Keep the device awake]
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* https://developer.android.com/media/platform/mediaplayer[Android - MediaPlayer Overview]
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* https://developer.android.com/develop/sensors-and-location/sensors/sensors_overview[Android - Sensors Overview]
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