如何使用databinding in kotlin

1.首先关键是配置好gradle：

in build.gradle(project): 

ext.gradle_version = '3.0.1'

 in build.gradle(app)

apply plugin: 'kotlin-kapt'

android{
....
dataBinding{
        enabled = true
    }
}

dependencies{
...
kapt "com.android.databinding:compiler:$gradle_version"
}

//kapt "com.android.databinding:compiler:$gradle_version" 可以不用的 

2.layout:

<layout xmlns:android="http://schemas.android.com/apk/res/android">


    <data>
        <variable
            name="user"
            type="com.m.databindingdemo.model.User"/>
    </data>

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.firstname}"
            />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.lastname}"
            />


    </LinearLayout>

</layout>

3.User:(注意，field不能private，要不会读取不了）

class User( val firstname: String,  val lastname: String)

4.activity：

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
        var user = User("Test", "User")
        binding.user = user
    }