使用包含标签的 Android 数据绑定

Question

Update note:

The above example works properly , because release 1.0-rc4 fixed the issue of needing the unnecessary variable.

Original question:

I do exactly as it is described in the documentation and it does not work:

main.xml:

<layout xmlns:andr...
    <data>
    </data>
       <include layout="@layout/buttons"></include>
....

buttons.xml:

<layout xmlns:andr...>
    <data>
    </data>
    <Button
        android:id="@+id/button"
        ...." />

MyActivity.java:

 ... binding = DataBindingUtil.inflate...
binding.button; ->cannot resolve symbol 'button'

how to get button?

Answer 1

The problem is that the included layout isn't being thought of as a data-bound layout. To make it act as one, you need to pass a variable:

buttons.xml:

<layout xmlns:andr...>
  <data>
    <variable name="foo" type="int"/>
  </data>
  <Button
    android:id="@+id/button"
    ...." />

main.xml:

<layout xmlns:andr...
...
   <include layout="@layout/buttons"
            android:id="@+id/buttons"
            app:foo="@{1}"/>
....

Then you can access buttons indirectly through the buttons field:

MainBinding binding = MainBinding.inflate(getLayoutInflater());
binding.buttons.button

As of 1.0-rc4 (just released), you no longer need the variable. You can simplify it to:

buttons.xml:

<layout xmlns:andr...>
  <Button
    android:id="@+id/button"
    ...." />

main.xml:

<layout xmlns:andr...
...
   <include layout="@layout/buttons"
            android:id="@+id/buttons"/>
....

Answer 2

Easy Complete Example

Just set id to included layout, and use binding.includedLayout.anyView .

This example helps passing a value to <include & accessing included views in code.

Step 1

You have layout_common.xml , want to pass String to included layout.

You will create String variable in layout and refer this String to TextView .

<data>
    // declare fields
    <variable
        name="passedText"
        type="String"/>
</data>

<TextView
    android:id="@+id/textView"
    ...
    android:text="@{passedText}"/> //set field to your view.

Step 2

Include this layout to parent layout. Give an id to included layout, so that we can use that in binding class. Now you can pass String passedText to your <include tag.

activity_main.xml

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

    <LinearLayout
        ..
        >

        <include
            android:id="@+id/includedLayout"
            layout="@layout/layout_common"
            app:passedText="@{@string/app_name}" // here we pass any String 
            />

    </LinearLayout>
</layout>

• You can use now binding.includedLayout.textView in your class.

• You can pass any variables to included layout like above.

   ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main); binding.includedLayout.textView.setText("text");

Note Both layouts (parent & included) should be binding layout , wrapped with <layout

Answer 3

just set an id for your include layout

    <include
        android:id="@+id/layout"
        layout="@layout/buttons" />

then

BUTTONSBINDING binding = yourMainBinding.layout;

BUTTONSBINDING is res/layout/buttons.xml

now :

binding.button.setText("simple_Way");

Answer 4

An other interesting thing on this is that you can pas variables to the imported layout from the binder like this:

MainBinding binding = MainBinding.inflate(getLayoutInflater());
binding.buttons.setVariable(BR.varID, variable)

Answer 5

You can make your bind work on your include just adding a ID to it like so:

<include
            android:id="@+id/loading"
            layout="@layout/loading_layout"
            bind:booleanVisibility="@{viewModel.showLoading}" />

Answer 6

it seems you have empty data tag in your xml file please cross check, it is making cause to not generate include layout file

 <data>

</data>

remove this tag if your not using, will solve the problem

Answer 7

I would like to add, I had the similar problem. My problem was that the variable name was title, the same as id name. There was no compile error. (Not 100% sure was that a problem, I also clean the project)

<?xml version="1.0" encoding="utf-8"?>
<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">
<data>

    <variable
        name="title"
        type="String" />
</data>
...
<androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/title"...>
<androidx.appcompat.widget.AppCompatTextView>
...
</layout>

Answer 8

Just you make sure your include layout has enabled dataBinding tag

below code is my layout that I include in other layout

<data>

    <variable
        name="backBinding"
        type="String" />

</data>

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/cl_back"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="@dimen/dimen_30"
    android:layout_marginTop="@dimen/dimen_30"
    android:padding="@dimen/dimen_2"
    app:layout_constraintStart_toStartOf="parent">

    <ImageView
        android:id="@+id/iv_back"
        android:layout_width="@dimen/dimen_10"
        android:layout_height="@dimen/dimen_20"
        android:contentDescription="@string/back"
        android:src="@drawable/ic_back"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tv_back"
        style="@style/AidoFTTextStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/dimen_10"
        android:text="@string/face_training"
        android:textSize="@dimen/text_20"
        app:layout_constraintBottom_toBottomOf="@id/iv_back"
        app:layout_constraintStart_toEndOf="@id/iv_back"
        app:layout_constraintTop_toTopOf="@id/iv_back" />

</androidx.constraintlayout.widget.ConstraintLayout>

here I am including in my main layout

<data>

    <variable
        name="viewModel"
        type="com.ingenDynamic.coreaidokotlin.viewModels.VideoCallViewModel" />

</data>

<androidx.constraintlayout.widget.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"
    android:background="@drawable/aido_main_background"
    tools:context=".ui.aidoVideoCall.ContactActivity">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/back_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="@dimen/dimen_20"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/cl_appBar">

        <include
            android:id="@+id/back"
            layout="@layout/app_back_layout"
            />

    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

and directly I can access my included layout

binding.backLayout.setOnClickListener { finish() }

binding.back.tvBack.text = getText(R.string.video_call)