surfaceCreated: java.lang.NullPointerException

Question

मैं कस्टम कैमरा ऐप बनाने के लिए कोशिश कर रहा हूँ, लेकिन जब भी मैं अपने कार्यक्रम चलाने,

हो रही -

दुर्भाग्य से अनुप्रयोग बंद कर दिया है

LogCat :

05-30 14:47:09.844: D/CameraCaptureActivity(797): getCameraInstance()Camera:: null 
05-30 14:47:09.855: D/CameraCaptureActivity(797): getCameraInstance()open:: null 
05-30 14:47:09.855: D/CameraCaptureActivity(797): mCamera:: null 
05-30 14:47:09.895: D/CameraCaptureActivity(797): mCamera :: null 
05-30 14:47:09.895: D/CameraCaptureActivity(797): mSurfaceHolder :: android.view.SurfaceView$4@40d06ef8 
05-30 14:47:09.924: D/CameraCaptureActivity(797): mCameraPreview :: com.example.demo.CameraPreview{40d06860 V.E..... ......I. 0,0-0,0} 
05-30 14:47:09.924: D/CameraCaptureActivity(797): FrameLayout :: android.widget.FrameLayout{40cfa7d8 V.E..... ......I. 0,0-0,0 #7f080000 app:id/camera_preview} 
05-30 14:47:09.954: D/CameraCaptureActivity(797): captureButton :: android.widget.Button{40cfad50 VFED..C. ......I. 0,0-0,0 #7f080001 app:id/button_capture} 
05-30 14:47:04.327: D/AndroidRuntime(797): Shutting down VM 
05-30 14:47:04.327: W/dalvikvm(797): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 
05-30 14:47:04.458: E/AndroidRuntime(797): FATAL EXCEPTION: main 
05-30 14:47:04.458: E/AndroidRuntime(797): java.lang.NullPointerException 
05-30 14:47:04.458: E/AndroidRuntime(797): at com.example.demo.CameraPreview.surfaceCreated(CameraPreview.java:33) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.updateWindow(SurfaceView.java:569) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView.access$000(SurfaceView.java:86) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:174) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:680) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1842) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer.doFrame(Choreographer.java:532) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.handleCallback(Handler.java:725) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Handler.dispatchMessage(Handler.java:92) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.os.Looper.loop(Looper.java:137) 
05-30 14:47:04.458: E/AndroidRuntime(797): at android.app.ActivityThread.main(ActivityThread.java:5041) 
05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invokeNative(Native Method) 
05-30 14:47:04.458: E/AndroidRuntime(797): at java.lang.reflect.Method.invoke(Method.java:511) 
05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
05-30 14:47:04.458: E/AndroidRuntime(797): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
05-30 14:47:04.458: E/AndroidRuntime(797): at dalvik.system.NativeStart.main(Native Method) 

त्रुटि:

java.lang.NullPointerException 

पंक्ति:

mCamera.setPreviewDisplay(surfaceHolder); 

CameraPreview.java:

public class CameraPreview extends SurfaceView implements 
SurfaceHolder.Callback { 

public static final String LOG_TAG = "CameraPreview"; 
private SurfaceHolder mSurfaceHolder; 
private Camera mCamera; 

// Constructor that obtains context and camera 
@SuppressWarnings("deprecation") 
public CameraPreview(Context context, Camera camera) { 
super(context); 
this.mCamera = camera; 
Log.d(CameraCaptureActivity.LOG_TAG, "mCamera :: " +mCamera); 
this.mSurfaceHolder = this.getHolder(); 
this.mSurfaceHolder.addCallback(this); 
this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
Log.d(CameraCaptureActivity.LOG_TAG, "mSurfaceHolder :: " +mSurfaceHolder); 
} 

@Override 
public void surfaceCreated(SurfaceHolder surfaceHolder) { 
try { 
    mCamera.setPreviewDisplay(surfaceHolder); 
    Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (setPreview) :: " +mCamera); 
    mCamera.startPreview(); 
    Log.d(CameraCaptureActivity.LOG_TAG, "surfaceCreated (startPreview) :: " +mCamera); 
} catch (IOException e) { 
    // left blank for now 
} 
} 

@Override 
public void surfaceDestroyed(SurfaceHolder surfaceHolder) { 
mCamera.stopPreview(); 
Log.d(CameraCaptureActivity.LOG_TAG, "surfaceDestroyed (stopPreview) :: " +mCamera); 
mCamera.release(); 
} 

@Override 
public void surfaceChanged(SurfaceHolder surfaceHolder, int format, 
    int width, int height) { 
// start preview with new settings 
try { 
    mCamera.setPreviewDisplay(surfaceHolder); 
    mCamera.startPreview(); 
} catch (Exception e) { 
    // intentionally left blank for a test 
} 
} 
} 

CameraCaptureActivity.java:

public static final String LOG_TAG = "CameraCaptureActivity"; 

private Camera mCamera; 

private CameraPreview mCameraPreview; 

/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    mCamera = getCameraInstance(); 
    Log.d(CameraCaptureActivity.LOG_TAG, "mCamera:: " + mCamera); 
    mCameraPreview = new CameraPreview(this, mCamera); 
    Log.d(CameraCaptureActivity.LOG_TAG, "mCameraPreview :: " + mCameraPreview); 
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); 
    preview.addView(mCameraPreview); 
    Log.d(CameraCaptureActivity.LOG_TAG, "FrameLayout :: " + preview); 

    Button captureButton = (Button) findViewById(R.id.button_capture); 
    Log.d(CameraCaptureActivity.LOG_TAG, "captureButton :: " + captureButton); 
    captureButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      mCamera.takePicture(null, null, mPicture); 
      Log.d(CameraCaptureActivity.LOG_TAG, "mCamera.takePicture :: " + mCamera); 
     } 
    }); 
} 

/** 
* Helper method to access the camera returns null if it cannot get the 
* camera or does not exist 
* 
* @return 
*/ 
private Camera getCameraInstance() { 
    Camera camera = null; 
    Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()Camera:: " + camera); 
    try { 
     camera = Camera.open(); 
     Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()open:: " + camera); 
    } catch (Exception e) { 
     // cannot get camera or does not exist 
    } 
    return camera; 
} 

PictureCallback mPicture = new PictureCallback() { 
    @Override 
    public void onPictureTaken(byte[] data, Camera camera) { 
     File pictureFile = getOutputMediaFile(); 
     if (pictureFile == null) { 
      return; 
     } 
     try { 
      FileOutputStream fos = new FileOutputStream(pictureFile); 
      fos.write(data); 
      fos.close(); 
     } catch (FileNotFoundException e) { 

     } catch (IOException e) { 
     } 
    } 
}; 

private static File getOutputMediaFile() { 
    File mediaStorageDir = new File(
      Environment 
        .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), 
      "MyCameraApp"); 
    if (!mediaStorageDir.exists()) { 
     if (!mediaStorageDir.mkdirs()) { 
      Log.d("MyCameraApp", "failed to create directory"); 
      return null; 
     } 
    } 
    // Create a media file name 
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss") 
      .format(new Date()); 
    File mediaFile; 
    mediaFile = new File(mediaStorageDir.getPath() + File.separator 
      + "IMG_" + timeStamp + ".jpg"); 

    return mediaFile; 
} 
} 

Answer 1

यहां आप mCamera शून्य लौट रहे हैं। यह कैमरे के अनुचित प्रारंभिकरण के कारण है। इसे आरंभ करने के लिए Camera.open(); का उपयोग करें। प्रारंभिक प्रक्रिया में फेंकने वाले किसी भी अपवाद की भी जांच करें। यह भी सुनिश्चित करें कि आपके पास मेनिफेस्ट फ़ाइल

<uses-permission android:name="android.permission.CAMERA" /> 


<uses-feature android:name="android.hardware.camera.autofocus" /> 

<uses-feature android:name="android.hardware.camera" /> 


try { 
    camera = Camera.open(); 
    Log.d(CameraCaptureActivity.LOG_TAG, "getCameraInstance()open:: " + camera); 
} catch (Exception e) { 
    // Check here for any exceptions 
} 

Answer 2

में सभी आवश्यक अनुमतियां हैं, तो कृपया नीचे दिए गए उत्तर देखें।

Custom_CameraActivity.java

public class Custom_CameraActivity extends Activity { 
private Camera mCamera; 
private CameraPreview mCameraPreview; 
/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    mCamera = getCameraInstance(); 
    mCameraPreview = new CameraPreview(this, mCamera); 
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview); 
    preview.addView(mCameraPreview); 
    Button captureButton = (Button) findViewById(R.id.button_capture); 
    captureButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      mCamera.takePicture(null, null, mPicture); 
     } 
    }); 
} 
/** 
* Helper method to access the camera returns null if it cannot get the 
* camera or does not exist 
* 
* @return 
*/ 
private Camera getCameraInstance() { 
    Camera camera = null; 
    try { 
     camera = Camera.open(); 
    } catch (Exception e) { 
     // cannot get camera or does not exist 
    } 
    return camera; 
    } 
PictureCallback mPicture = new PictureCallback() { 
    @Override 
    public void onPictureTaken(byte[] data, Camera camera) { 
     File pictureFile = getOutputMediaFile(); 
     if (pictureFile == null) { 
      return; 
     } 
     try { 
      FileOutputStream fos = new FileOutputStream(pictureFile); 
      fos.write(data); 
      fos.close(); 
     } catch (FileNotFoundException e) { 
     } catch (IOException e) { 
     } 
    } 
}; 
private static File getOutputMediaFile() { 
    File mediaStorageDir = new File(
      Environment 
        .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), 
      "MyCameraApp"); 
    if (!mediaStorageDir.exists()) { 
     if (!mediaStorageDir.mkdirs()) { 
      Log.d("MyCameraApp", "failed to create directory"); 
      return null; 
     } 
    } 
    // Create a media file name 
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss") 
      .format(new Date()); 
    File mediaFile; 
    mediaFile = new File(mediaStorageDir.getPath() + File.separator 
      + "IMG_" + timeStamp + ".jpg"); 
    return mediaFile; 
    } 
} 

CameraPreview.java

public class CameraPreview extends SurfaceView implements 
SurfaceHolder.Callback { 
private SurfaceHolder mSurfaceHolder; 
private Camera mCamera; 
// Constructor that obtains context and camera 
@SuppressWarnings("deprecation") 
public CameraPreview(Context context, Camera camera) { 
    super(context); 
    this.mCamera = camera; 
    this.mSurfaceHolder = this.getHolder(); 
    this.mSurfaceHolder.addCallback(this); 
    this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
} 
@Override 
public void surfaceCreated(SurfaceHolder surfaceHolder) { 
    try { 
     mCamera.setPreviewDisplay(surfaceHolder); 
     mCamera.startPreview(); 
    } catch (IOException e) { 
     // left blank for now 
    } 
} 
@Override 
public void surfaceDestroyed(SurfaceHolder surfaceHolder) { 
    mCamera.stopPreview(); 
    mCamera.release(); 
} 
@Override 
public void surfaceChanged(SurfaceHolder surfaceHolder, int format, 
     int width, int height) { 
    // start preview with new settings 
    try { 
     mCamera.setPreviewDisplay(surfaceHolder); 
     mCamera.startPreview(); 
    } catch (Exception e) { 
     // intentionally left blank for a test 
    } 
    } 
} 

main.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:orientation="horizontal" > 
<FrameLayout 
    android:id="@+id/camera_preview" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:layout_weight="1" /> 
<Button 
    android:id="@+id/button_capture" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="center" 
    android:text="Capture" /> 
</LinearLayout> 

अपनी AndroidManifest.xml फ़ाइल में पंक्तियाँ नीचे जोड़े

<uses-feature android:name="android.hardware.camera" /> 
    <uses-permission android:name="android.permission.CAMERA" /> 
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />