Null pointer exception on bitmap while scrolling

Question

I am creating a bitmap which hold Facebook image cropped in a circular shape the code was working fine but wen there is a lot of images in the same activity its giving a null pointer exception while scrolling here is my code

//enter code here
byte[] decodedString = Base64.decode(obj.picture, Base64.DEFAULT);
                            Bitmap decodedByte =  BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
                     on this line i am getting a null pointer exception
                            Bitmap circleBitmap = Bitmap.createBitmap(decodedByte.getWidth(), decodedByte.getHeight(), Bitmap.Config.ARGB_8888);
                            BitmapShader shader = new BitmapShader(decodedByte, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
                            Paint paint = new Paint();
                            paint.setShader(shader);
                            Canvas c = new Canvas(circleBitmap);
                            c.drawCircle(decodedByte.getWidth() / 2, decodedByte.getHeight() / 2, decodedByte.getWidth() / 2, paint);
                            holder.civilianImage.setImageBitmap(circleBitmap);

i can see the image presented but while i scroll this error is shown. Any help would be appreciated. And one more thing i getting the image from Facebook but each image is different from the other one in resolution and while cropping the image is losing a lot of it how can i manage this also.

enter code here
public class ListViewAdapter extends ArrayAdapter<NewsFeed>
{
    public static final int missionLayout = 0;
    public static final int badgeLayout = 1;
    private static final int TYPE_MAX_COUNT = badgeLayout + 1;
    private NewsFeed obj;
    private LayoutInflater mInflater;
    public ListViewAdapter ()
    {
        super(CityNewsFeedActivity.this,R.layout.activity_activity_city_news_feed,newsfeed);
        mInflater=(LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    @Override
    public int getViewTypeCount()

    {
        return TYPE_MAX_COUNT;
    }

    @Override
    public int getItemViewType(int position)
    {
         obj = newsfeed.get(position);
        return obj.category.equals("mission")? missionLayout : badgeLayout;
    }


    @Override
    public View getView(final int position, View convertView, ViewGroup parent)
    {
        ViewHolder holder=null;

        if (convertView == null)
        {

            holder = new ViewHolder();
   if (obj.accepted_rejected.equals("success"))
                        {
                            holder.relativeLayoutMission.setBackgroundResource(R.drawable.mission_successful);
                            Float alpha = Float.valueOf("0.9");
                            holder.relativeLayoutMission.setAlpha(alpha);
                            byte[] decodedString = Base64.decode(obj.picture, Base64.DEFAULT);
                            Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
                            Bitmap circleBitmap = Bitmap.createBitmap(decodedByte.getWidth(), decodedByte.getHeight(), Bitmap.Config.ARGB_8888);
                            BitmapShader shader = new BitmapShader(decodedByte, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
                            Paint paint = new Paint();
                            paint.setShader(shader);
                            Canvas c = new Canvas(circleBitmap);
                            c.drawCircle(decodedByte.getWidth() / 2, decodedByte.getHeight() / 2, decodedByte.getWidth() / 2, paint);
                            holder.civilianImage.setImageBitmap(circleBitmap);
                          }
                      }
                return convertView;
                  }
                 }
enter code here
11-02 20:36:11.344  30864-30864/net.httpiamheroic.herioc E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: net.httpiamheroic.herioc, PID: 30864
java.lang.NullPointerException
        at net.httpiamheroic.herioc.net.httpiamherioc.Activities.CityNewsFeedActivity$ListViewAdapter.getView(CityNewsFeedActivity.java:419)
        at android.widget.AbsListView.obtainView(AbsListView.java:2450)
        at android.widget.ListView.makeAndAddView(ListView.java:1891)
        at android.widget.ListView.fillDown(ListView.java:792)
        at android.widget.ListView.fillGap(ListView.java:756)
        at android.widget.AbsListView.trackMotionScroll(AbsListView.java:5728)
        at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:4826)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:807)
        at android.view.Choreographer.doCallbacks(Choreographer.java:601)
        at android.view.Choreographer.doFrame(Choreographer.java:561)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:791)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:157)
        at android.app.ActivityThread.main(ActivityThread.java:5867)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:674)
        at dalvik.system.NativeStart.main(Native Method)

We need to know whether you used only one image or adapter in scroll view. Also if Adapter, how is it implemented? — Suneel Prakash, Nov 02 '14 at 18:55
Its a listView which is set to an adapter and in the getView i am calling the above code @SuneelPrakash — Mostafa Addam, Nov 02 '14 at 18:57
@SuneelPrakash i updated my code can u look at it please. Thank you — Mostafa Addam, Nov 02 '14 at 19:04
@TacB0sS Bitmap circleBitmap = Bitmap.createBitmap(decodedByte.getWidth(), decodedByte.getHeight(), Bitmap.Config.ARGB_8888); — Mostafa Addam, Nov 02 '14 at 19:10
Which means that decodedByte is null which means that the decodedString is not an image or not one that Android can create, which means that the content of obj.picture is not what you expect... try to add a print to the obj.picture length at 416... — TacB0sS, Nov 02 '14 at 19:15
Also see this answer for a more constructive pattern to use http://stackoverflow.com/questions/26362854/listview-how-to-access-items-elements-programmatically-from-outside/26567212#26567212 — TacB0sS, Nov 02 '14 at 19:16

Suneel Prakash · Answer 1 · 2014-11-02T19:27:28.650

Change your getView method like this Also check what if obj.accepted_rejected.equals("success") is false

 @Override
    public View getView(final int position, View convertView, ViewGroup parent)
    {
        ViewHolder holder=null;
        // Your row view 
        View rowView = convertView;

        if (rowView == null)
        {
            // New holder object 
            holder = new ViewHolder();
            holder.civilianImage = rowView.findViewById(R.id.civilianimageview);// Your xml image view id

                            rowView.setTag(holder);

           } else{
                // Use existing holder object 
              holder=(ViewHolder) rowView.getTag();
           }
        if (obj.accepted_rejected.equals("success")){
            holder.relativeLayoutMission.setBackgroundResource(R.drawable.mission_successful);
            Float alpha = Float.valueOf("0.9");
            holder.relativeLayoutMission.setAlpha(alpha);
            byte[] decodedString = Base64.decode(obj.picture, Base64.DEFAULT);
            Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
            Bitmap circleBitmap = Bitmap.createBitmap(decodedByte.getWidth(), decodedByte.getHeight(), Bitmap.Config.ARGB_8888);
            BitmapShader shader = new BitmapShader(decodedByte, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            Paint paint = new Paint();
            paint.setShader(shader);
            Canvas c = new Canvas(circleBitmap);
            c.drawCircle(decodedByte.getWidth() / 2, decodedByte.getHeight() / 2, decodedByte.getWidth() / 2, paint);
            holder.civilianImage.setImageBitmap(circleBitmap);
        }else{
            // Handle this case
        }
          return rowView;
     }

what is rowView? and yes i am handling the else of the if(obj.accepted_rejected.equals("success")) but still the error is presented — Mostafa Addam, Nov 02 '14 at 19:21
Changed code you have to use bitmap creation every time not only when convertview is null. Please try and let me know. — Suneel Prakash, Nov 02 '14 at 19:28
the problem is when i scroll fast directly when the activity launch it crashes but when i do it gently it don't weird — Mostafa Addam, Nov 02 '14 at 19:48
You need to have a loader till minimum views are fetched that is first one. Bitmap processing normally takes time — Suneel Prakash, Nov 03 '14 at 05:36

score 0 · Answer 2 · answered Nov 05 '14 at 21:02

Unfortunately(Stupidly) multiple methods that has to do with image handling in Android does not throw an exception when provided data that is not an image, they simply return null... WTH?

So as it seems the reason for the error is due to a wrong input to:

byte[] decodedByte = BitmapFactory.decodeByteArray(...)

Which returns null, and forces the app to crash on the next line trying to use the decodedByte

Bitmap circleBitmap = Bitmap.createBitmap(decodedByte.getWidth(), decodedByte.getHeight(), Bitmap.Config.ARGB_8888);

Null pointer exception on bitmap while scrolling

2 Answers2