CODEWITHSUNDEEP
javaandroidopencvnullpointerexceptioncamera
Sumeet Batra
Sumeet Batra

Reputation: 357

Android Auto Exposure Lock Null Pointer Exception

I am developing an opencv app for android and am trying to lock my camera's auto exposure. I have been following the tutorial 3 sample in OpenCV4Android in order to access the various camera parameters. I have made a custom camera class for accessing the camera properties.

Full error:

NullPointerException: Attempt to invoke virtual method 'android.hardware.Camera$Parameters 
android.hardware.Camera.getParameters() on a null object reference
at {PackageName}.MainView.lockAutoExposure()

This is my MainView class so far (the custom camera class):

public class MainView extends JavaCameraView {

private static final String TAG = "Urop::MainView";

public MainView(Context context, AttributeSet attrs) {
    super(context, attrs);
}

@SuppressWarnings("deprecation")
public void lockAutoExposure() {
    Camera.Parameters params = mCamera.getParameters();
    params.setAutoExposureLock(true);
    mCamera.setParameters(params);
}


}

Here is where I instantiate the class and set it up in the main activity: 

private MainView mOpenCvCameraView;

private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch(status) {
        case LoaderCallbackInterface.SUCCESS:
        {
            Log.i(TAG, "Loaded Successfully");
            mOpenCvCameraView.enableView();
            mOpenCvCameraView.setMaxFrameSize(640, 480);
            mOpenCvCameraView.lockAutoExposure();
            System.loadLibrary("opencvnative");


            break;
        }
    ...

My permissions in the manifest. Not sure if I need anything else:

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

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

If anyone can help, I would greatly appreciate it!

Upvotes: 1

Views: 286

Answers (2)

Sumeet Batra
Sumeet Batra

Reputation: 357

Solved it by moving lockAutoExposure to the onCameraViewStarted() method.

Upvotes: 1

Bill
Bill

Reputation: 4646

mCamera is a null object. It is failing because you are trying to call getParameters() on something that does not exist (unless you are not showing us the full code?)

Upvotes: 0

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