Kotlin中的Android:Google Codelabs从该项目进行数据绑定时出错 [英] Android in Kotlin: Error in Databinding from the project by Google codelabs

问题描述

我正在做Google提供的这门课程，

I was doing this course offered by Google, https://codelabs.developers.google.com/codelabs/kotlin-android-training-data-binding-basics/index.html?index=..%2F..android-kotlin-fundamentals#2,

github中的特定代码: https ://github.com/google-developer-training/android-kotlin-fundamentals-apps/tree/master/AboutMeDataBinding

The particular code in github: https://github.com/google-developer-training/android-kotlin-fundamentals-apps/tree/master/AboutMeDataBinding

在这里，我正在进行数据绑定，逐步显示了如何实现它.但是最后我得到了一个错误 ActivityMainBinding

Here I was doing the data binding, which is shown step by step how to implement it. But at the end I was getting an error with ActivityMainBinding

我已经从github下载了他们的解决方案代码，该代码在使用Android-studio 3.4.1打开时遇到了同样的问题.

I have downloaded their solution code from github which on opening with Android-studio 3.4.1 , I got the same problem.

在主要Acctivity.kt

In Main Acctivity.kt

  package com.example.android.aboutme
    import android.content.Context
     import android.os.Bundle
     import android.view.View
   import android.view.inputmethod.InputMethodManager
  import androidx.appcompat.app.AppCompatActivity 
   import androidx.databinding.DataBindingUtil
   import com.example.android.aboutme.databinding.ActivityMainBinding

 class MainActivity : AppCompatActivity() {

private lateinit var binding: ActivityMainBinding

private val myName: MyName = MyName("Aleks Haecky")

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = DataBindingUtil.setContentView(this, 
R.layout.activity_main)

    binding.myName = myName

    binding.doneButton.setOnClickListener {
        addNickname(it)
    }

}


 private fun addNickname(view: View) {
    binding. apply {
        myName?.nickname = nicknameEdit.text.toString()
        invalidateAll()
        nicknameEdit.visibility = View.GONE
        doneButton.visibility = View.GONE
        nicknameText.visibility = View.VISIBLE
    }

    // Hide the keyboard.
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    imm.hideSoftInputFromWindow(view.windowToken, 0)
}
}

Build.gradle(module:app)

Build.gradle(module:app)

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.android.aboutme"
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    dataBinding {
        enabled = true
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.0.2'
    testImplementation 'junit:junit:4.12'
}

我希望一切都很好，但ActivityMainBinding为红色.错误提示未解决的引用.

I expected to be all okay but ActivityMainBinding was red in colour. Error says unresolved reference.

IDE Fatal Error:
java.lang.NullPointerException
    at com.intellij.build.MultipleBuildsView.lambda$onEvent$2(MultipleBuildsView.java:218)
    at com.intellij.build.MultipleBuildsView.lambda$onEvent$4(MultipleBuildsView.java:310)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.doRun(LaterInvocator.java:435)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.runNextEvent(LaterInvocator.java:419)
    at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:403)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:762)
    at java.awt.EventQueue.access$500(EventQueue.java:98)
    at java.awt.EventQueue$3.run(EventQueue.java:715)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:732)
    at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:755)
    at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:704)
    at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:391)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

Unresolved reference: ActivityMainBinding
Unresolved reference: ActivityMainBinding
Unresolved reference: it
Unresolved reference: nicknameEdit
Unresolved reference: invalidateAll
Unresolved reference: nicknameEdit
Unresolved reference: doneButton
Unresolved reference: nicknameText

推荐答案

我通过试用方法得到了这个答案.我们需要简单地清理项目，然后进行重建. 为此，我们可以简单地省略(或删除)以灰色显示的导入(即，在项目中是不必要的).然后，Build->Clean Project 然后是Build->Rebuild Project.

I got this answer by a trial method. We need to simply, Clean the project followed by Rebuilding. For this to be done, we can simply omit(or delete) the imports which are depicted in grey (i.e. they are unnecessary in the project). Then, Build->Clean Project and after that Build->Rebuild Project.

这篇关于Kotlin中的Android:Google Codelabs从该项目进行数据绑定时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！