CODEWITHSUNDEEP
androidandroid-asynctaskandroid-viewpagerbitmapfactoryandroid-pageradapter
user5897135
user5897135

Reputation:

Reason behind null pointer exception?

i am using pager adapter to display images in view pager ,that will be downloaded by bitmapfactory in asynctask.

pageradapter class:

public class pageradapter extends PagerAdapter {
    Button load_img;
    ImageView imgview;
    Bitmap bitmap;



    Context mContext;
    LayoutInflater mLayoutInflater;
    List<String> l = MainActivity.list;
    ImageLoader mImageLoader;

    public pageradapter(Context context) {
        mContext = context;


    }

    @Override
    public int getCount() {
        return 4;
    }


    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageLoader mImageLoader = ImageLoader.getInstance();
        mLayoutInflater = ((LayoutInflater) container.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE));
        View view = mLayoutInflater.inflate(R.layout.img, container, false);
          imgview = (ImageView) view.findViewById(R.id.imageView3);

Bitmap btp=new LoadImage().doInBackground(l.get(position));
        imgview.setImageBitmap(btp);

        container.addView(view);

        return view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((LinearLayout) object);
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    public class LoadImage extends AsyncTask<String, String, Bitmap> {

        ProgressDialog pDialog = new ProgressDialog(mContext);
        @Override
        protected void onPreExecute() {
            super.onPreExecute();

            pDialog.setMessage("Loading Image ....");
            pDialog.show();

        }
        protected Bitmap doInBackground(String... args) {

            try {
                bitmap = BitmapFactory.decodeStream((InputStream) new URL(args[0]).getContent());

            } catch (Exception e) {
                e.printStackTrace();
            }
            return bitmap;
        }

        protected void onPostExecute(Bitmap image) {

            if(image != null){
                imgview.setImageBitmap(image);
                pDialog.dismiss();

            }else{

                pDialog.dismiss();
                Toast.makeText(mContext, "Image Does Not exist or Network Error", Toast.LENGTH_SHORT).show();

            }
        }
    }

}

my logcat:

02-08 18:49:22.554 18345-18345/autogenie.dg10 E/AndroidRuntime: FATAL EXCEPTION: main java.lang.NullPointerException at autogenie.dg10.pageradapter$LoadImage.doInBackground(pageradapter.java:89) at autogenie.dg10.pageradapter.instantiateItem(pageradapter.java:54) at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:870) at android.support.v4.view.ViewPager.populate(ViewPager.java:1020) at android.support.v4.view.ViewPager.populate(ViewPager.java:952) at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474) at android.view.View.measure(View.java:15518) at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:681) at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461) at android.view.View.measure(View.java:15518) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135) at android.view.View.measure(View.java:15518) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391) at android.view.View.measure(View.java:15518) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.view.View.measure(View.java:15518) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) at android.view.View.measure(View.java:15518) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176) at android.view.View.measure(View.java:15518) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) at android.view.Choreographer.doCallbacks(Choreographer.java:562) at android.view.Choreographer.doFrame(Choreographer.java:532) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) at android.os.Handler.handleCallback(Handler.java:725) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:5041) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) at dalvik.system.NativeStart.main(Native Method)

Upvotes: 0

Views: 153

Answers (1)

Rohit5k2
Rohit5k2

Reputation: 18112

Wrong way to call AsyncTask. You don't directly call doInBackground().

Change 

Bitmap btp=new LoadImage().doInBackground(l.get(position));

to

Bitmap btp = new LoadImage().execute(l.get(position));

Upvotes: 0

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