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kotlin - 在使用 Android 数据绑定(bind)和 Kotlin 的自定义 BindingAdapter 中使用 lambda

转载 作者:行者123 更新时间:2023-12-02 12:23:05 25 4
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我正在尝试使用 Kotlin 为 Android 数据绑定(bind)的 lambda 处理程序进行自定义绑定(bind)。只要我的 ViewModel 处理程序显式返回 Void,它就可以正常工作。但如果它返回 Kotlin Unit,我会得到 error: cannot generate view binders java.lang.StackOverflowError .

一切似乎都正确连接,因为所有其他自定义绑定(bind)都有效(convertBooleanToViewVisibility、toTestString 甚至 customOnClick,只要我调用 onClickVoid [参见下面的示例])。

问题是当我试图在我的应用程序中调用返回 Unit 的 lambda 时:customOnClick 而不是返回 Void。在下面的例子中,它是调用 mainViewModel.onClick()而不是 mainViewModel.onClickVoid() .必须有一种方法让它工作,因为 android:onClick 能够调用 Unit版本。但是,如果我对 customOnClick 调用 onClick 使用相同的语法,我会收到此错误:

:app:kaptGenerateStubsDebugKotlin
Using kotlin incremental compilation
:app:kaptDebugKotlin
e: error: cannot generate view binders java.lang.StackOverflowError
e:

e: at android.databinding.tool.writer.Scope.access$getCurrentScope$cp(LayoutBinderWriter.kt:49)
e: at android.databinding.tool.writer.Scope$Companion.getCurrentScope(LayoutBinderWriter.kt:58)
e: at android.databinding.tool.writer.LayoutBinderWriterKt.scopedName(LayoutBinderWriter.kt:196)
e: at android.databinding.tool.expr.Expr.toCode(Expr.java:776)
e: at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt:203)
e: at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt)
e: at android.databinding.tool.ext.LazyExt.getValue(ext.kt:27)
e: at android.databinding.tool.writer.LayoutBinderWriterKt.getCallbackLocalName(LayoutBinderWriter.kt)
e: at android.databinding.tool.writer.LayoutBinderWriterKt.scopedName(LayoutBinderWriter.kt:197)
e: java.lang.IllegalStateException: failed to analyze: java.lang.RuntimeException: failure, see logs for details.
cannot generate view binders java.lang.StackOverflowError
at android.databinding.tool.writer.Scope.access$getCurrentScope$cp(LayoutBinderWriter.kt:49)
at android.databinding.tool.writer.Scope$Companion.getCurrentScope(LayoutBinderWriter.kt:58)
at android.databinding.tool.writer.LayoutBinderWriterKt.scopedName(LayoutBinderWriter.kt:196)
at android.databinding.tool.expr.Expr.toCode(Expr.java:776)
at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt:203)
at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt)
at android.databinding.tool.ext.LazyExt.getValue(ext.kt:27)
at android.databinding.tool.writer.LayoutBinderWriterKt.getCallbackLocalName(LayoutBinderWriter.kt)
at android.databinding.tool.writer.LayoutBinderWriterKt.scopedName(LayoutBinderWriter.kt:197)
.............................. (TRUNCATED) ...................................
at android.databinding.tool.expr.Expr.toCode(Expr.java:776)
at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt:203)
at android.databinding.tool.writer.LayoutBinderWriterKt$callbackLocalName$2.invoke(LayoutBinderWriter.kt)
at android.databinding.tool.ext.LazyExt.getValue(ext.kt:27)
at android.databinding.tool.writer.LayoutBinderWriterKt.getCallbackLocalName(LayoutBinderWriter.kt)
at android.databinding.tool.writer.LayoutBinderWriterKt.scopedName(LayoutBinderWriter.kt:197)

at org.jetbrains.kotlin.analyzer.AnalysisResult.throwIfError(AnalysisResult.kt:57)
at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules(KotlinToJVMBytecodeCompiler.kt:144)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:167)
at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:55)
at org.jetbrains.kotlin.cli.common.CLICompiler.exec(CLICompiler.java:182)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.execCompiler(CompileServiceImpl.kt:397)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.access$execCompiler(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1$2.invoke(CompileServiceImpl.kt:365)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1$2.invoke(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$2$$special$$inlined$withValidClientOrSessionProxy$lambda$1.invoke(CompileServiceImpl.kt:798)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$2$$special$$inlined$withValidClientOrSessionProxy$lambda$1.invoke(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.common.DummyProfiler.withMeasure(PerfUtils.kt:137)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.checkedCompile(CompileServiceImpl.kt:825)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.access$checkedCompile(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$2.invoke(CompileServiceImpl.kt:797)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$doCompile$2.invoke(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.ifAlive(CompileServiceImpl.kt:1004)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.ifAlive$default(CompileServiceImpl.kt:865)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.doCompile(CompileServiceImpl.kt:791)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.access$doCompile(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1.invoke(CompileServiceImpl.kt:364)
at org.jetbrains.kotlin.daemon.CompileServiceImpl$compile$1.invoke(CompileServiceImpl.kt:99)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.ifAlive(CompileServiceImpl.kt:1004)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.ifAlive$default(CompileServiceImpl.kt:865)
at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:336)
at sun.reflect.GeneratedMethodAccessor86.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:324)
at sun.rmi.transport.Transport$1.run(Transport.java:200)
at sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:683)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)



... 39 more


FAILED

知道如何使它与 Unit 一起工作,所以我不需要更改我的 ViewModel 来显式返回 Void?对于我所有的处理程序?

示例项目

项目构建.gradle
buildscript {
ext.kotlin_version = '1.1.3-2'
ext.plugin_version = '2.3.3'

repositories {
jcenter()
}

dependencies {
classpath "com.android.tools.build:gradle:$plugin_version"
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}
}

allprojects {
repositories {
jcenter()
mavenCentral()
}
}

task clean(type: Delete) {
delete rootProject.buildDir
}

模块(应用程序)build.gradle
buildscript {
repositories {
jcenter()
mavenCentral()
}

dependencies {
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
}
}

apply plugin: 'com.android.application'
apply plugin: "kotlin-android"
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'

android {
compileSdkVersion 24
buildToolsVersion "25.0.2"
defaultConfig {
applicationId "com.example.kotlindatabinding"
minSdkVersion 24
targetSdkVersion 24
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}

dataBinding {
enabled = true
}

buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}

sourceSets {
main.java.srcDirs += 'src/main/kotlin'
}
}

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:26.+'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
testCompile 'junit:junit:4.12'
compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"

kapt "com.android.databinding:compiler:$plugin_version"
}

kapt {
generateStubs = true
}

MainActivity.kt
class MainActivity : AppCompatActivity() {

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

val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
binding.setMainViewModel(MainViewModel())
}
}

主视图模型.kt
class MainViewModel {
val myName: String
get() {
return "Hello world!"
}

fun onClick(){
Log.i("ME", "Logging...")
}

fun onClickVoid(): Void? {
onClick()
return null as Void?
}
}

绑定(bind).kt
object Bindings{
@BindingConversion
@JvmStatic fun convertBooleanToViewVisibility(isVisible: Boolean): Int {
// Working
return if (isVisible) View.VISIBLE else View.GONE
}

@BindingAdapter("customOnClick")
@JvmStatic fun setOnItemClicked(textView: TextView, consumer: (String) -> Any?) {
// Working
consumer("test")
}

@JvmStatic fun toTestString(input: Any) : String {
return "Test"
}
}

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>
<import type="com.example.kotlindatabinding.Bindings"/>
<variable
name="mainViewModel"
type="com.example.kotlindatabinding.MainViewModel" />
</data>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.kotlindatabinding.MainActivity">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{Bindings.toTestString(mainViewModel.myName)}"
android:visibility="@{mainViewModel.myName != null}"
android:clickable="true"
android:onClick="@{() -> mainViewModel.onClick()}"
app:customOnClick="@{(someInput) -> mainViewModel.onClickVoid()}" />
</LinearLayout>
</layout>

最佳答案

好吧,我想回复很晚,但其他人可能有同样的问题:
据我所知,这是一个错误的假设:数据绑定(bind)使用 Java,一般不了解 Kotlin。
为了通过数据绑定(bind)设置监听器,您必须使用带有方法的 Java 接口(interface)。 Kotlin lambdas 不像具有简单方法的 Java 接口(interface),因为它们包含函数,这意味着它们总是返回一些东西(如果未指定,则返回 Unit)。

所以要实现设置监听器,在绑定(bind)适配器中定义一个简单的Java接口(interface)作为参数

关于kotlin - 在使用 Android 数据绑定(bind)和 Kotlin 的自定义 BindingAdapter 中使用 lambda,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45639221/

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