昨天,我将我的 Android Studio 更新到了 3.1。所以我只能使用Databinding V2。我可以在Java中成功构建。但在Kotlin中失败。它告诉我Unresolved reference: BR
布局
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="mainViewModel"
type="com.example.shao.myapplication.ViewModel" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{mainViewModel.title}"/>
</LinearLayout>
</layout>
在Java中
public class MainActivity2 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
binding.setVariable(BR.mainViewModel, new ViewModel());
}
public static int getMainBr() {
return BR.mainViewModel;
}
在 Kotlin 中
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val mBinding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
mBinding.setVariable(BR.mainViewModel, ViewModel())
}
}
最佳答案
Android 与 Kotlin 的数据绑定(bind)
首先,在 Android Studio 中创建好 Android 项目后,我们需要将 Data Binding 依赖和 Kotlin 的依赖添加到我们应用的 build.gradle 文件中。
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-kapt'
android {
....
dataBinding {
enabled = true
}
}
dependencies {
...
// notice that the compiler version must be the same than our gradle version
kapt 'com.android.databinding:compiler:2.3.1'
}
首先我们需要创建一个模型。在这种情况下,基本的像 User.kt
data class User(val name: String, val age: Int)
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<variable
name="user"
type="com.kuma.sample.User"
/>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.kuma.sample.MainActivity"
>
<TextView
android:id="@+id/user_name_text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp"
android:text="@{user.name}"
tools:text="Name"
/>
<TextView
android:id="@+id/user_age_text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp"
android:text="@{Integer.toString(user.age)}"
tools:text="XX"
/>
</LinearLayout>
</layout>
Kotlin 类
package com.kuma.sample
import android.databinding.DataBindingUtil
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import com.kuma.kotlinsteps.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
val user = User("Kuma", 23)
binding.setVariable(BR.user, user)
binding.executePendingBindings()
}
}
解决错误Br
enter code hereapply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
compileSdkVersion 24
buildToolsVersion "24.0.0"
defaultConfig {
applicationId "com.example.icarusud.recyclerviewtest"
minSdkVersion 15
targetSdkVersion 24
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
dataBinding {
enabled true
}
sourceSets {
main.java.srcDirs += 'src/main/kotlin'
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:24.1.1'
compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
//recyclerview
compile "com.android.support:recyclerview-v7:24.1.1"
//lastadapter
compile 'com.github.nitrico.lastadapter:lastadapter:1.1.1'
kapt "com.android.databinding:compiler:2.1.2"
}
repositories {
mavenCentral()
}
kapt { generateStubs = true }
根据下面的代码更改你的 gradle 设置试试这个代码它可以帮助你。
关于android - Databinding V2 和 kotlin,我找不到我的 BT?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49526041/