Java – Android Studio Data Binding (bind) does not allow element data here

I’m trying to make a tick-tac-toe android app (albeit using a 4×4 grid). I decided to use the button to depict each grid square block and wanted to use data binding (bind) on the button to the data in a String[][] array that would represent the grid internally. I try to do something similar to the one presented here http://www.vogella.com/tutorials/AndroidDatabinding/article.html So I created this class :

public class ModelJoc extends BaseObservable{

private String[][] tabla_joc;

public ModelJoc() {
    for (String[] line : tabla_joc)
        for (String element : line)
            element = "";

tabla_joc[0][0] = "M";
    tabla_joc[0][1] = "W";
}

Then add data binding (bind) to activity_main.xml:

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.tgeorge.temajoc.MainActivity">
<data>
    <variable
        name="state"
        type="com.example.tgeorge.temajoc.ModelJoc"/>
</data>

Then try setting the text of the button to a value in the array:

 <Button
        android:id="@+id/button1"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:text="@={state.getBlockState()[0][0]}"/>

But it gives me these errors: “Element data is not allowed here” and “Attribute is missing android: prefix”. I can’t tell from the examples in the tutorial what I’m doing wrong, so the question is where should I put them?

I

think I understand the problem now. You must use <layout> to outline your layout label:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        tools:context="com.example.tgeorge.temajoc.MainActivity">
    <data>
      <variable
          name="state"
          type="com.example.tgeorge.temajoc.ModelJoc"/>
    </data>
    <android.support.constraint.ConstraintLayout 
        android:layout_width="match_parent"
        android:layout_height="match_parent">

<!-- ... -->
        <Button
            android:id="@+id/button1"
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:text="@{state.getBlockState()[0][0]}"/>

If you don’t, Android Data Binding (BIND) will not recognize it as a Data Binding (BIND) layout file.