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Android

Posted by Yev Tarler
Yev Tarler
Courses Plus Student 820 Points

Ribbit crashes when trying to implement a custom list Adapter ( NullPointerException )

i'm in "Retrieving and Viewing Messages" Android part.

I've used exactly the same MessageAdapter class, and XML layout file, same goes for the reume method in inboxFragment.

But i get this error:

05-17 11:27:39.986: E/AndroidRuntime(5172): FATAL EXCEPTION: main 05-17 11:27:39.986: E/AndroidRuntime(5172): Process: com.example.yevsnap, PID: 5172 05-17 11:27:39.986: E/AndroidRuntime(5172): java.lang.NullPointerException 05-17 11:27:39.986: E/AndroidRuntime(5172): at com.example.yevsnap.MessageAdapter.getView(MessageAdapter.java:46) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.AbsListView.obtainView(AbsListView.java:2240) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.ListView.makeAndAddView(ListView.java:1790) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.ListView.fillDown(ListView.java:691) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.ListView.fillFromTop(ListView.java:752) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.ListView.layoutChildren(ListView.java:1630) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.AbsListView.onLayout(AbsListView.java:2091) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1055) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1589) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:374) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.View.layout(View.java:14817) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewGroup.layout(ViewGroup.java:4631) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1987) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1744) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.Choreographer.doCallbacks(Choreographer.java:574) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.Choreographer.doFrame(Choreographer.java:544) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.os.Handler.handleCallback(Handler.java:733) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.os.Handler.dispatchMessage(Handler.java:95) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.os.Looper.loop(Looper.java:136) 05-17 11:27:39.986: E/AndroidRuntime(5172): at android.app.ActivityThread.main(ActivityThread.java:5017) 05-17 11:27:39.986: E/AndroidRuntime(5172): at java.lang.reflect.Method.invokeNative(Native Method) 05-17 11:27:39.986: E/AndroidRuntime(5172): at java.lang.reflect.Method.invoke(Method.java:515) 05-17 11:27:39.986: E/AndroidRuntime(5172): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 05-17 11:27:39.986: E/AndroidRuntime(5172): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 05-17 11:27:39.986: E/AndroidRuntime(5172): at dalvik.system.NativeStart.main(Native Method)

1 Answer

Yev Tarler
PLUS
Yev Tarler
Courses Plus Student 820 Points
Yev Tarler
Yev Tarler
Courses Plus Student 820 Points

Hey teamTreeHouse, apparently you didn't set: convertView.setTag(holder);

in the block where you instantiate the holder. It fixed it for me, no clue how it worked for you, maybe because it was an older version.

Juan Carlos Hernández
Juan Carlos Hernández
8,316 Points

Thanks !!

Nicholas McKay
Nicholas McKay
Courses Plus Student 2,181 Points

Bingo! Thanks. Just for clarity, the full block for instantiating the convertView now looks like this:

        if (convertView == null) {
            convertView = LayoutInflater.from(mContext).inflate(R.layout.message_item, null);
            holder = new ViewHolder();
            holder.iconImageView = (ImageView) convertView.findViewById(R.id.message_icon);
            holder.nameLabel = (TextView) convertView.findViewById(R.id.message_sender);
            convertView.setTag(holder);
        }
        else {
            holder = (ViewHolder) convertView.getTag();
        }

This is actually covered in the video "Maintaining Scroll Position in a ListView".