未解决的参考数据库-AndroidStudio4.0

Question

我一直收到错误：“未解决的引用:绑定”和“未解决的引用: ActivityMainBinding”。

我正在使用AndroidStudio4.0，Android插件版本: 4.0.0和Gradle版本6.1.1。

build.gradle (模块: app)：

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

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.example.twowaydatabinding"
        minSdkVersion 24
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

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

    buildFeatures {
        dataBinding = true
        viewBinding = true
    }
}

dependencies {
    def lifecycle_version = "2.2.0"

    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.3.0'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    // ViewModel
    implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"
    // LiveData
    implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"
}

build.gradle (项目)：

buildscript {
    ext.kotlin_version = "1.3.72"
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.0.0"
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

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

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="com.example.twowaydatabinding.MainActivityViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
        <!-- layout content -->
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

MainActivity.kt：

package com.example.twowaydatabinding

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.ViewModelProvider
import com.example.twowaydatabinding.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private lateinit var viewModel : MainActivityViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        binding = DataBindingUtil.setContentView(this,R.layout.activity_main)
        viewModel = ViewModelProvider(this).get(MainActivityViewModel::class.java)
        binding.viewModel = viewModel
        binding.lifecycleOwner = this
    }
}

MainActivityViewModel.xml：

package com.example.twowaydatabinding

import androidx.databinding.Bindable
import androidx.databinding.Observable
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel

class MainActivityViewModel : ViewModel(), Observable {

    @Bindable
    val userName = MutableLiveData<String>()

    init {
        userName.value = "Frank"
    }

    override fun removeOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {
        TODO("Not yet implemented")
    }

    override fun addOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback?) {
        TODO("Not yet implemented")
    }
}

我试过：

• 构建->清洁项目，然后构建->重建项目
• 文件->使缓存无效/重新启动

但什么都帮不上忙。类ActivityMainBinding从不生成。

当我转到import com.example.twowaydatabinding.databinding.ActivityMainBinding的MainActivity.kt声明时，它会将我重定向到activity_main.xml。代码没有显示任何错误，但是当我试图构建项目时，这些绑定错误就会显示出来。

我做错了什么？

Answer 1

而不是这一行

buildFeatures {
        dataBinding = true
        viewBinding = true
    }

写这行

buildFeatures {
        dataBinding true
        viewBinding true
    }

在主要活动中试试这个，

 binding = ActivityMainBinding.inflate(layoutInflater)
 setContentView(binding.root)

Answer 2

，，这对我有用

1)删除".gradle“文件夹，删除".idea”文件夹，并删除app文件夹下的构建文件夹

2)点击“文件->失效缓存/重新启动”

Answer 3

在build.gradle中添加像这样的数据绑定(Module:app)

  defaultConfig {
    dataBinding {
        enabled true
    }
}