无法使用数据绑定 Android 从 ViewModel 与 XML 通信

Question

我正在尝试使用MVVM模式从xml与viewmodel进行通信，反之亦然。我以前从事过数据绑定工作，并成功地使用实时数据 - dagger - MVVM。 最近，我尝试创建一个新项目，从那时起我无法使用 XML 和视图模型跟踪响应。来自 XML ->ViewModel的 onClick 和从View -> XML为文本视图赋值都不起作用。但是没有崩溃或任何东西，只是它不起作用。我已经添加了所有相关文件[ MainActivity， activity_main， viewModel， Dagger Module， build.gradle ]

如果有人能告诉我这里出了什么问题，我将不胜感激。

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"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="viewmodel"
type="aveek.com.vm.ui.home.MainActivityViewModel"/>
</data>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{viewmodel.balanceText}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:clickable="true"
android:onClick="@{() -> viewmodel.clickData()}"
app:layout_constraintTop_toTopOf="parent" />
...
</layout>

MainActivity.kt

class MainActivity : AppCompatActivity(),LifecycleOwner {
@Inject
lateinit var binding : ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
AndroidInjection.inject(this)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
binding.setLifecycleOwner(this) 
with(binding){
this.viewmodel?.let {
it.balanceText.set( "Aveek testing")
it.data.observe(this@MainActivity, Observer {
Toast.makeText(this@MainActivity, "Data is now : $it", Toast.LENGTH_SHORT).show()
})
}
}
}

MainActivityViewModel.kt

class MainActivityViewModel : ViewModel() {
val data = MutableLiveData<Boolean>()
val balanceText = ObservableField<String>()
fun clickData(){
data.value = false
}
}

MainActivityModule.kt

@Module
class  MainActivityModule{
/**
* provides binding to  Main Activity from respective XML
* @property viewModel
* @property context
* @return binding of the view
*/
@Provides
fun binding(context: MainActivity, viewModel : MainActivityViewModel) : 
ActivityMainBinding {
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(context, 
R.layout.activity_main)
binding.viewmodel = viewModel
return binding
}
}

build.gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android {
compileSdkVersion 27
defaultConfig {
applicationId "aveek.test"
minSdkVersion 15
targetSdkVersion 27
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
vectorDrawables.useSupportLibrary = true
}
dataBinding {
enabled = true
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 
'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}
kapt {
generateStubs = true
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
implementation 'com.android.support:multidex:1.0.2'
implementation 'com.android.support:design:27.1.1'
implementation "android.arch.lifecycle:extensions:1.1.0"
//    annotationProcessor "android.arch.lifecycle:compiler:1.1.0"
kapt "com.android.databinding:compiler:$androidPluginVersion"
annotationProcessor "com.google.dagger:dagger-compiler:$daggerVersion"
annotationProcessor "com.google.dagger:dagger-android-processor:$daggerVersion"
kapt "com.google.dagger:dagger-compiler:$daggerVersion"
kapt "com.google.dagger:dagger-android-processor:$daggerVersion"

implementation "com.google.dagger:dagger:$daggerVersion"
implementation "com.google.dagger:dagger-android:$daggerVersion"
implementation "com.google.dagger:dagger-android-support:$daggerVersion"
kapt "com.google.dagger:dagger-compiler:$daggerVersion"
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso- 
core:3.0.2'
}

ext{
kotlin_version = '1.2.31'
androidPluginVersion = '3.1.0'
daggerVersion = '2.13'
}

Answer 1

您将无法使用任何生成的方法来将变量设置为绑定，因为除了 ViewDataBinding 之外没有公共超类，因此您将被迫使用反射，或者您可以使用方便的方法 setVariable()：

binding.setVariable(BR.viewModel, viewModel);

Answer 2

正如我所怀疑的，问题出在dagger注射上。也许我以错误的方法实现，但如果在没有 DI 的情况下运行，视图模型完全没问题。

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewModel = ViewModelProviders.of(this).get(MainActivityViewModel::class.java)
binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
binding.viewmodel = viewModel
binding.setLifecycleOwner(this)
mLifecycleRegistry = LifecycleRegistry(this).apply {
markState(Lifecycle.State.CREATED)
}
with(binding){
this.viewmodel?.let {
it.balanceText.set( "Aveek testing")
it.data.observe(this@MainActivity, Observer {
Toast.makeText(this@MainActivity, "Data is now : $it", 
Toast.LENGTH_SHORT).show()
})
}
}
}

所以，我已经浏览了DI代码，发现在MainActivity.onCreate() 我正在这样做

AndroidInjection.inject(this)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)

这基本上覆盖了数据绑定行为。所以我像这样更新了代码

AndroidInjection.inject(this)
super.onCreate(savedInstanceState)
//setContentView(R.layout.activity_main)
// and initiated binding here as injecting binding from module before setting content won't be effective
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)

并删除

//    @Inject
//    lateinit var binding : ActivityMainBinding

现在它工作得很好..