[안드로이드][카메라]java.lang.RuntimeException: cancelAutoFocus failed

카메라 기능을 사용하여 테스트 하는 과정에 오류가 하나 발생하였다.  액티비티 창을 휴대폰의 뒤로 가기 버튼을 사용하면서 발생하였다. 

    ............................
    private ZXingScannerView mScannerView;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_full_scanner);
        
        mScannerView = new ZXingScannerView(this);
        contentFrame.addView(mScannerView);

        // Toogle autofocus:
        //mScannerView.setAutoFocus(true);

        mScannerView.setResultHandler(this);

        // this paramter will make your HUAWEI phone works great!
        //mScannerView.setAspectTolerance(0.5f);

        mScannerView.startCamera();
    }
    
    ...................

java.lang.RuntimeException: cancelAutoFocus failed
        at android.hardware.Camera.native_cancelAutoFocus(Native Method)
        at android.hardware.Camera.cancelAutoFocus(Camera.java:1399)
        at me.dm7.barcodescanner.core.CameraPreview.stopCameraPreview(CameraPreview.java:120)
        at me.dm7.barcodescanner.core.CameraPreview.surfaceDestroyed(CameraPreview.java:79)
        at android.view.SurfaceView.updateSurface(SurfaceView.java:861)
        at android.view.SurfaceView.windowStopped(SurfaceView.java:235)
        at android.view.ViewRootImpl.setWindowStopped(ViewRootImpl.java:1573)
        at android.view.WindowManagerGlobal.setStoppedState(WindowManagerGlobal.java:647)
        at android.app.Activity.performStop(Activity.java:8035)
        at android.app.ActivityThread.callActivityOnStop(ActivityThread.java:4616)
        at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:4594)
        at android.app.ActivityThread.handleStopActivity(ActivityThread.java:4669)
        at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:233)
        at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

[해결법]

카메라 모듈 사용 후 종료시, 반환해야한다. onBackPressed()메소드를 오버라이드하여 카메라 모듈 사용을 종료 후 finish()를 호출한다.

    @Override
    public void onBackPressed() {
        if(mScannerView!=null)
            mScannerView.stopCamera();
        mScannerView = null;

        finish();
    }