Android camera permission

Question

I have this code which i make using official developer android sites. I want to create camera preview, but first ask for permissions. When i start the app they crash, but before app exit, they ask me for permissions which i grant, and then app crash. After i enter app again it work just fine, but i want to get rid of that crash. Anyone know a solution?

CameraActivity.java

public class CameraActivity extends AppCompatActivity {

    private Camera mCamera;
    private CameraPreview mPreview;
    private static final int PERMISSION_CAMERA = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.CAMERA)
                != PackageManager.PERMISSION_GRANTED) {

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                    Manifest.permission.CAMERA)) {

                // Show an explanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.

            } else {

                // No explanation needed, we can request the permission.

                ActivityCompat.requestPermissions(this,
                        new String[]{Manifest.permission.CAMERA},
                        PERMISSION_CAMERA);

                // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
                // app-defined int constant. The callback method gets the
                // result of the request.
            }
        }

        // Create an instance of Camera
        mCamera = getCameraInstance();

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
            case PERMISSION_CAMERA: {
                // If request is cancelled, the result arrays are empty.
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                    // permission was granted, yay! Do the
                    // contacts-related task you need to do.

                } else {

                    // permission denied, boo! Disable the
                    // functionality that depends on this permission.
                }
                return;
            }

            // other 'case' lines to check for other
            // permissions this app might request.
        }
    }

    @Override
    public void onPause() {
        super.onPause();
        // Stop camera access
        releaseCamera();
    }

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e){
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }

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

Logcat

FATAL EXCEPTION: main
Process: com.example.ivan.cameratest1, PID: 7690
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.hardware.Camera.setPreviewDisplay(android.view.SurfaceHolder)' on a null object reference
at com.example.ivan.cameratest1.CameraPreview.surfaceCreated(CameraPreview.java:36)
at android.view.SurfaceView.updateWindow(SurfaceView.java:656)
at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:172)
at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:1013)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2542)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1537)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7183)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:959)
at android.view.Choreographer.doCallbacks(Choreographer.java:734)
at android.view.Choreographer.doFrame(Choreographer.java:670)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:945)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)

Your title does not describe the problem or question, you don't tell us what the error is, and you don't give us the logcat output. Please fix these things. — takendarkk, Feb 21 '18 at 17:33

score 1 · Answer 1 · answered Jul 23 '18 at 05:16

private final String TAG = "Debug_MainActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    checkCameraPermission();
}


private final int MY_PERMISSIONS_REQUEST_USE_CAMERA = 0x00AF;
private void checkCameraPermission(){
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA ) != PackageManager.PERMISSION_GRANTED) {
        Log.d(TAG,"Permission not available requesting permission");
            ActivityCompat.requestPermissions(this,
                                                new String[]{Manifest.permission.CAMERA}, MY_PERMISSIONS_REQUEST_USE_CAMERA);
    } else {
        Log.d(TAG,"Permission has already granted");
    }
}


@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_USE_CAMERA: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Log.d(TAG,"permission was granted! Do your stuff");
            } else {
                Log.d(TAG,"permission denied! Disable the function related with permission.");
            }
            return;
        }
    }
}

score 0 · Answer 2 · answered Feb 21 '18 at 17:38

I think you are getting an error with permission.. You are trying to open camera even when you don't have permission to. That's why it crashes on first start up and not on second time.

Try to perform the changes below (I changed onCreate and onRequestPermissionsResult):

public class CameraActivity extends AppCompatActivity {

    private Camera mCamera;
    private CameraPreview mPreview;
    private static final int PERMISSION_CAMERA = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.CAMERA)
                != PackageManager.PERMISSION_GRANTED) {

            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.CAMERA},
                    PERMISSION_CAMERA);
            }
        } else {
            mCamera = getCameraInstance();
        }

        // Create our Preview view and set it as the content of our activity.
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mPreview);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String permissions[], int[] grantResults) {
        switch (requestCode) {
            case PERMISSION_CAMERA: {
                if (grantResults.length > 0
                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    mCamera = getCameraInstance();
                }
                return;
            }
        }
    }

    ...
}

Android camera permission

2 Answers2