java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getBottom()' on a null object reference

Question

It's working fine when I build and run it. But I'm getting this error when I relaunch the app remotely.

this is the only place where I used views. It's in ListAdapter.

I looked around on both Google and StackOverflow and I have found some information. However, I have not got it to work. Now I hope that I can get help with my code.

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getBottom()' on a null object reference
        at android.widget.ListView.fillDown(ListView.java:829)
        at android.widget.ListView.fillFromTop(ListView.java:888)
        at android.widget.ListView.layoutChildren(ListView.java:1958)
        at android.widget.AbsListView.onLayout(AbsListView.java:2991)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at com.google.android.material.appbar.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:142)
        at com.google.android.material.appbar.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:41)
        at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1556)
        at androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:888)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at com.android.internal.policy.DecorView.onLayout(DecorView.java:1075)
        at android.view.View.layout(View.java:22406)
        at android.view.ViewGroup.layout(ViewGroup.java:6594)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3394)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2863)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1911)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8526)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
        at android.view.Choreographer.doCallbacks(Choreographer.java:761)
        at android.view.Choreographer.doFrame(Choreographer.java:696)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7078)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:974)

public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        if(getItem(position)!= null) {
            title = getItem(position).getText();
            date = getItem(position).getDate();
            hour = getItem(position).getHour();
            minute = getItem(position).getMinute();
            SimpleDateFormat formatter = new SimpleDateFormat("dd MMMM yyyy");
            LayoutInflater inflater = LayoutInflater.from(context);
            convertView = inflater.inflate(resource, parent, false);
            TextView titleView = (TextView) convertView.findViewById(R.id.title);
            TextView descpView = (TextView) convertView.findViewById(R.id.description);
            TextView dateView = (TextView) convertView.findViewById(R.id.date);
            titleView.setText(title);
            descpView.setText(hour + ":" + minute);
            dateView.setText(formatter.format(date));
        }

        return convertView;
    }

Zain · Accepted Answer · 2020-12-05 11:50:37Z

2

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getBottom()' on a null object reference

Some view is getting null causing NullPointerException when calling getBottom() on that view.

So, as the app runs locally without this issue; but not remotely, so the answer will be a kind of a guess.

Assumption 1: getView returns a null value.

Reason: convertView is marked as @Nullable, so it can be null from the beginning, and can remain null if the condition if(getItem(position)!= null) is not met; and therefore getView() can return a null View.

Recommendation: you need to make sure that getView can't return null value by setting the convertView value outside the if condition like the below snippet.

public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    if (converView == null) {
        convertView = inflater.inflate(resource, parent, false);
    }

Assumption 2: convertView is null from this expression convertView = inflater.inflate(resource, parent, false);

Reason: You didn't provide from where you got the resource argument you pass to inflate(); maybe it's a variable value that can change in multiple values; one of which can be null; and therefore making convertView null as well.

Recommendation:

If the resource is not changeable, you can hardcode it by setting its value to say R.layout.list_row; where list_row is the xml layout of your list item.

And If it's changeable, then debug its value to make sure it can't be null by any means.

edited Dec 5, 2020 at 11:50

answered May 29, 2020 at 18:06

Zain

41.3k10 gold badges70 silver badges95 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Zain Over a year ago

@NoorHossain just modified it

Noor Hossain Over a year ago

Thanks Your second Assumption works for me, then one question, so, what is best practice to send the resource layout as a parameter ?

Zain Over a year ago

@NoorHossain welcome.. It depends on the code... Generally speaking you can pass initial value to the adapter constructor and save it into a local field .. And create a setter for this field and call it whenever need to change the value. This value should be integer that refer to a layout restore file.. If theres no a layout resource for this value then a NPE will be raised

Collectives™ on Stack Overflow

java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getBottom()' on a null object reference

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related