Android Data Binding crash when using include tag with custom view layout

Question

I'm trying to add some custom view using include tag to my activity layout which using DataBinding. My custom view is using DataBinding as well. But I got crash on application start:

05-02 17:30:03.685 12595-12595/? E/AndroidRuntime: FATAL EXCEPTION: main
                                                   Process: com.novachevskyi.databindingtest, PID: 12595
                                                   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.novachevskyi.databindingtest/com.novachevskyi.databindingtest.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.novachevskyi.databindingtest.databinding.CustomViewBinding.invalidateAll()' on a null object reference
                                                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                       at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                       at android.os.Handler.dispatchMessage(Handler.java:102)
                                                       at android.os.Looper.loop(Looper.java:148)
                                                       at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                       at java.lang.reflect.Method.invoke(Native Method)
                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.novachevskyi.databindingtest.databinding.CustomViewBinding.invalidateAll()' on a null object reference
                                                       at com.novachevskyi.databindingtest.databinding.ActivityMainBinding.invalidateAll(ActivityMainBinding.java:41)
                                                       at com.novachevskyi.databindingtest.databinding.ActivityMainBinding.<init>(ActivityMainBinding.java:33)
                                                       at com.novachevskyi.databindingtest.databinding.ActivityMainBinding.bind(ActivityMainBinding.java:105)
                                                       at android.databinding.DataBinderMapper.getDataBinder(DataBinderMapper.java:11)
                                                       at android.databinding.DataBindingUtil.bind(DataBindingUtil.java:185)
                                                       at android.databinding.DataBindingUtil.bindToAddedViews(DataBindingUtil.java:299)
                                                       at android.databinding.DataBindingUtil.setContentView(DataBindingUtil.java:279)
                                                       at android.databinding.DataBindingUtil.setContentView(DataBindingUtil.java:261)
                                                       at com.novachevskyi.databindingtest.MainActivity.onCreate(MainActivity.java:11)
                                                       at android.app.Activity.performCreate(Activity.java:6251)
                                                       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                                                       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                                                       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                       at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                       at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                       at android.os.Looper.loop(Looper.java:148) 
                                                       at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                       at java.lang.reflect.Method.invoke(Native Method) 
                                                       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

MainActivity:

public class MainActivity extends AppCompatActivity {
  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    DataBindingUtil.setContentView(this, R.layout.activity_main);
  }
}

CustomView:

public class CustomView extends LinearLayout {
  public CustomView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  @Override protected void onFinishInflate() {
    super.onFinishInflate();
    DataBindingUtil.bind(this);
  }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

  <RelativeLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      android:paddingBottom="@dimen/activity_vertical_margin"
      tools:context="com.novachevskyi.databindingtest.MainActivity">

    <include layout="@layout/custom_view"/>

  </RelativeLayout>

</layout>

custom_view.xml:

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android">

  <com.novachevskyi.databindingtest.CustomView
      android:layout_width="match_parent"
      android:layout_height="match_parent">

    <TextView
        android:text="Hello World!"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

  </com.novachevskyi.databindingtest.CustomView>

</layout>

I've also created public repo with sample project: https://github.com/novachevskyi/DataBinding-issue

I was using data binding with com.android.tools.build:gradle:1.3.1 and now, when I've tried to upgrade build tools version to com.android.tools.build:gradle:2.1.0, I'm facing such issue with all my views that contain include xml tag. Will appreciate for any information about issue described above.

Answer 1

In case anyone else makes the er..dumb mistake I did...

This error was happening to me when I mistakenly had two duplicate layout files, one using databinding, and the other not...

Removing the duplicate fixed the error for me.

Answer 2

I took a look at your project and ran it. I think the reason it is crashing is because of

@Override protected void onFinishInflate() {
    super.onFinishInflate();
    DataBindingUtil.bind(this);
}

if you remove DataBindingUtil.bind(this) it will stop crashing. The reason being that the bind call is looking for a <layout>surrounding the view but it can't find it so it throws an exception. Since the CustomView is calling bind on itself it is not surrounded by anything causing ViewDataBinding to throw new IllegalArgumentException("View is not a binding layout")

I'm not entirely sure what you're trying to achieve but calling bind inside of onFinishInflate would be redundant since the activity is doing that for you when it binds the layout for the activity. If you require the binding within the CustomView class you can do the following:

@Override protected void onAttachedToWindow() {
  super.onAttachedToWindow();
  CustomViewBinding binding = DataBindingUtil.findBinding(this);
}