Zoom In & Out Custom Camera - Null Pointer Exception

Question

I am trying to Implement Zoom In & Out functionality in my Custom Camera.

    NullPointerException: zoomControls.setVisibility(View.GONE);

Answer 1

try this code :

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        // TODO Auto-generated method stub 

        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            Log.d(TAG, "mode=NONE");
            break;
        case MotionEvent.ACTION_MOVE:
            if (mode == ZOOM) {
                    float newDist = spacing(event);

                    double zoomDist = newDist-oldDist;

                    if(zoomDist > 0){
                        if(zoomDist > 50 && zoomDist <= 200){

                            if (curZoomLevel < mZoomMax && gestureZoom == 0) {
                                gestureZoom ++;
                                GestureZoomIn();
                            }

                        }else if(zoomDist > 200 && zoomDist <= 300){


                            if (curZoomLevel < mZoomMax && gestureZoom == 1) {

                                gestureZoom ++;
                                GestureZoomIn();
                            }
                        }else if(zoomDist > 300 && zoomDist <= 400){

                            if (curZoomLevel < mZoomMax && gestureZoom == 2) {

                                gestureZoom++;
                                GestureZoomIn();
                            }
            break;
        }

        view.setImageMatrix(matrix);
        return true;
    }


 private void GestureZoomIn(){
       if (mParameters.isZoomSupported()){
            mZoomMax = mParameters.getMaxZoom();
            if (zoom_text_value<mZoomMax) {
                zoom_text_value++;
                curZoomLevel++;
                zoom_float=zoom_float+0.5;
                onZoomValueChanged(curZoomLevel);

private void GestureZoomOut(){
       if (mParameters.isZoomSupported()){

            if (0<zoom_text_value) {
                zoom_text_value--;
                curZoomLevel--;
                zoom_float=zoom_float-0.5;
                onZoomValueChanged(curZoomLevel);

this might be help you.

Answer 2

In your code, params isn't ever initialized, thus its value is always null. This will result in a NullPointerException if you try to use a method on the null object. Perhaps in your constructor you should initialize it with the following:

params = mCamera.getParameters();