Android Bad Practices: Use of Released Camera Resource

The code references the Camera object after it has already been released.

The code attempts to use the Camera object after the it has already been released. Any further references to the Camera object without reacquiring the resource will throw an exception, and can cause the application to crash if the exception is not caught.

Example 1: The following code uses a toggle button to toggle the camera preview on and off. After the user taps the button once, the camera preview stops and the camera resource is released. However, if she taps the button again, startPreview() is called on the previously-released Camera object.

public class ReuseCameraActivity extends Activity {
  private Camera cam;

  ...
  private class CameraButtonListener implements OnClickListener {
      public void onClick(View v) {
          if (toggle) {
              cam.stopPreview();
              cam.release();
          }
          else {
              cam.startPreview();
          }
          toggle = !toggle;
      }
  }
  ...
}