使用Android数据绑定和Kotlin在自定义BindingAdapter中使用lambda
我正在尝试使用Kotlin为Android数据绑定创建一个带有lambda处理程序的自定义绑定。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单元,则会出现使用Android数据绑定和Kotlin在自定义BindingAdapter中使用lambda,kotlin,stack-overflow,android-databinding,kapt,Kotlin,Stack Overflow,Android Databinding,Kapt,我正在尝试使用Kotlin为Android数据绑定创建一个带有lambda处理程序的自定义绑定。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单元,则会出现错误:无法生成视图绑定java.lang.StackOverflowerError 所有其他自定义绑定都正常工作(convertbooleantovievisibility、toTestString甚至customOnClick,只要我调用onClickVoid[参见下面的示例]) 问题是当我试
错误:无法生成视图绑定java.lang.StackOverflowerError
所有其他自定义绑定都正常工作(convertbooleantovievisibility、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lambda返回单位时:customOnClick而不是返回Void。在下面的示例中,调用mainViewModel.onClick()
而不是mainViewModel.onClickVoid()
。一定有办法让它像android一样工作:onClick能够调用单元
版本。但如果我对customOnClick调用onClick使用相同的语法,则会出现以下错误:
: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$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
... 39 more
FAILED
您知道如何使它与Unit一起工作,这样我就不需要更改ViewModel来显式返回Void了吗?为了我所有的经纪人
样本项目
projectbuild.gradle
模块(应用程序)build.gradle
MainActivity.kt
绑定.kt
activity_main.xml
将此代码移到默认配置块之外。放进去
android {
dataBinding {
enabled = true
}
}
嗯,我想是很晚才回复,但其他人可能也有同样的问题: 就我所见,这是一个错误的假设:数据绑定使用Java,一般不了解Kotlin。 为了通过数据绑定设置侦听器,必须使用Java接口和方法。Kotlin Lambda不像Java接口那样具有简单的方法,因为它们包含函数,这意味着它们总是返回一些东西(如果没有指定,则返回Unit)
因此,为了实现设置一个侦听器,将一个简单的Java接口定义为绑定适配器中的一个参数True,我在编写示例时把它放错了位置。编辑了我的帖子并在我的示例中修复了它,但对stackoverflow没有任何帮助。我认为kotlin和databinding beucase存在一个bug,我也有同样的问题。
buildscript {
repositories {
jcenter()
mavenCentral()
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$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
}
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
binding.setMainViewModel(MainViewModel())
}
}
class MainViewModel {
val myName: String
get() {
return "Hello world!"
}
fun onClick(){
Log.i("ME", "Logging...")
}
fun onClickVoid(): Void? {
onClick()
return null as Void?
}
}
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"
}
}
<?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>
android {
dataBinding {
enabled = true
}
}