сбой при подключении камеры при закрытии при нажатии кнопки home

Question

В приложении моей камеры, когда я нажимаю кнопку «домой», появляется сообщение «К сожалению, тест (myappname) остановился». Я искал вокруг какое-то время, но никогда не могу избавиться от этой ошибки. Приветствуется любая помощь, я застрял на этом долгое время :(. Если я что-то не хватает просто спросить. Спасибо

public class MainActivity extends Activity implements OnInitListener, OnUtteranceCompletedListener{ 

private Camera myCamera; 
private MyCameraSurfaceView myCameraSurfaceView; 

Button myButton; 
Button speakButton; 
boolean recording; 

Button Speak; 
TextView TextBox; 
private TextToSpeech mTts; 


/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

} 


Button.OnClickListener speakButtonOnClickListener = new Button.OnClickListener() { 
    @Override 
    public void onClick(View v) { 
     //when Button Speak is clicked 
     //grab text from the EditText Speech 
     String TALK = TextBox.getText().toString(); //Talk now has text from EditText 
     mTts.speak(TALK, TextToSpeech.QUEUE_ADD, null); 
    }}; 

Button.OnClickListener myButtonOnClickListener 
     = new Button.OnClickListener(){ 

    @Override 
    public void onClick(View v) { 
     // TODO Auto-generated method stub 
     if(recording){ 
      // stop recording and release camera 
      myButton.setText("START"); 
      recording = false; 
     }else{ 
      recording = true; 
      myButton.setText("STOP"); 
     } 
    }}; 

private Camera getCameraInstance(){ 
// TODO Auto-generated method stub 
    Camera c = null; 
    try { 
     c = Camera.open(); // attempt to get a Camera instance 
     c.setDisplayOrientation(90); 
    } 
    catch (Exception e){ 
     // Camera is not available (in use or does not exist) 
    } 
    return c; // returns null if camera is unavailable 
} 

@Override 
protected void onPause() { 
    super.onPause(); 
    releaseCamera(); 
        // release the camera immediately on pause event 
} 

@Override 
protected void onResume() { 
    super.onResume(); 

    if (myCamera == null) { 
     getWindow().setFormat(PixelFormat.UNKNOWN); 
     requestWindowFeature(Window.FEATURE_NO_TITLE); 
     recording = false; 
     setContentView(R.layout.activity_main); 

     Speak = (Button)this.findViewById(R.id.button1); 
     TextBox = (TextView)this.findViewById(R.id.textView1); 
     //initialise TTS 
     mTts= new TextToSpeech(this, this); 

     //Get Camera for preview 
     myCamera = getCameraInstance(); 
     if(myCamera == null){ 
      Toast.makeText(MainActivity.this, 
        "Fail to get Camera", 
        Toast.LENGTH_LONG).show(); 
     } 


     myCameraSurfaceView = new MyCameraSurfaceView(this, myCamera); 
     FrameLayout myCameraPreview = (FrameLayout)findViewById(R.id.videoview); 
     myCameraPreview.addView(myCameraSurfaceView); 


     speakButton = (Button) findViewById(R.id.button1); 
     speakButton.setOnClickListener(speakButtonOnClickListener); 
    } 
} 

@Override 
protected void onStop() { 
    super.onStop(); 
    // release the camera immediately on pause event 
} 

@Override 
protected void onDestroy() { 
    super.onDestroy(); 
    // release the camera immediately on pause event 
    releaseCamera(); 

} 


private void releaseCamera(){ 
    if (myCamera != null){ 
     myCamera.stopPreview(); 
     myCamera.release();  // release the camera for other applications 
     myCamera = null; 
     myCamera.setPreviewCallback(null); 
    } 
} 

@SuppressWarnings("deprecation") 
@Override 
public void onInit(int status) { 
    mTts.setOnUtteranceCompletedListener(this); 
} 

@Override 
public void onUtteranceCompleted(String utteranceId) { 
    mTts.shutdown(); 
} 
} 

LogCat

10-04 16:00:23.330: E/AndroidRuntime(2871): FATAL EXCEPTION: main 
10-04 16:00:23.330: E/AndroidRuntime(2871): java.lang.RuntimeException: Unable to pause  activity {com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3064) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3019) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2997) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread.access$800(ActivityThread.java:141) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1267) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at  android.os.Handler.dispatchMessage(Handler.java:99) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.os.Looper.loop(Looper.java:137) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at java.lang.reflect.Method.invoke(Method.java:525) 
10-04 16:00:23.330: E/AndroidRuntime(2871):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 

Answer 1

Попробуйте this-

@Override 
    protected void onPause() { 
     super.onPause(); 
     if (mCamera != null) { 
      mCamera.stopPreview(); 
      mCamera.release(); 
      mCamera = null; 
     } 
    } 

Answer 2

Ошибка в методе releaseCamera:

private void releaseCamera(){ 
    if (myCamera != null){ 
     myCamera.stopPreview(); 
     myCamera.release();  // release the camera for other applications 
     myCamera = null; 
     myCamera.setPreviewCallback(null); 
    } 
} 

вы вызываете setPreviewCallback на null.

Решение: переместить myCamera.setPreviewCallback(null); наверху.