NullPointerException when using .addView to ViewGroup

Question

I'm trying to use .addView to add another LinearLayout to the ViewGroup.

I am getting the following error on LogCat:

05-21 16:23:04.096: E/AndroidRuntime(2086): FATAL EXCEPTION: main 05-21 16:23:04.096: E/AndroidRuntime(2086): java.lang.NullPointerException 05-21 16:23:04.096: E/AndroidRuntime(2086): at android.view.ViewGroup.addView(ViewGroup.java:3148) 05-21 16:23:04.096: E/AndroidRuntime(2086): at android.view.ViewGroup.addView(ViewGroup.java:3131)

This is the code being called:

final LinearLayout eventContainerSub =
                        (LinearLayout) findViewById(R.layout.event_container);

                final LinearLayout eventContainer =
                        (LinearLayout) findViewById(R.id.eventContainer);

                eventContainer.addView(eventContainerSub);

Here is the ViewGroup (the first linear layout):

<LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:animateLayoutChanges="true"
                android:id="@+id/eventContainer"
                android:weightSum="100"
                android:duplicateParentState="true">

And this is the (second) LinearLayout I'm adding to the (first one) LinearLayout above:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="horizontal"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:id="@+id/eventContainerSub">

Answer 1

Both containers have the exact same name..eventContainerSub.

There is no eventContainer, change the view group to be the container as you planned..

<LinearLayout
                android:orientation="horizontal"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:animateLayoutChanges="true"
                android:id="@+id/event_container"
                android:weightSum="100"
                android:duplicateParentState="true">

and make sure the code is asking for the right Ids:

final LinearLayout eventContainerSub = (LinearLayout) findViewById(R.layout.eventContainerSub);

            final LinearLayout eventContainer =
                    (LinearLayout) findViewById(R.id.event_container);

I'd also suggest you first remove the SubContainer from the view if it got inflated, as that view already has a parent and you cannot attach the SubContainer to two parents.

Either leave the subcontainer from this file and create a new one, or remove from the parent and only then add to the ViewGroup you want.

Android layout replacing a view with another view on run time

Call removeView() on the child's parent first