AndroidでdataBindingを実装する

dataBindingを有効にする

build.gradle

    dataBinding {
        enabled = true
    }

bindingするクラスを追加

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">

    <data>
        <!-- Userクラスにバインドする -->
        <variable
            name="user"
            type="com.herokuapp.aqueous_spire_22637.test.User"/>
    </data>
<LinearLayout
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.herokuapp.aqueous_spire_22637.test.MainActivity">

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:text="@{String.valueOf(user.id)}"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:text="@{user.name}"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"/>
</LinearLayout>
</layout>

Userクラスを定義して、ObservableFieldを使う

User.java

import android.databinding.ObservableField;
import android.databinding.ObservableInt;

public class User {
    public ObservableInt id = new ObservableInt();
    public ObservableField<String> name = new ObservableField<>();

    public User(Integer idInt, String nameString){
        id.set(idInt);
        name.set(nameString);
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setUser(new User(1, "joji"));
    }
}