kotlin 应用程序中的 DataBinding 出错

Question

我正在尝试在我的 kotlin android 应用程序中绑定数据，我在 codelab 上关注本教程 Link to Codelab 我做了所有相同的事情。

但是在 MainActitvity.kt 文件中导入 ActivityMainBinding 时 ide 一直以红色文本显示错误。

我确实在应用级别 gradle 文件中启用了数据绑定

dataBinding {
        enabled = true
    }

Here I have imported and initialized dataBinding

import android.content.Context
import android.databinding.DataBindingUtil
import android.hardware.input.InputManager
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.view.inputmethod.InputMethodManager
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
//import kotlinx.android.synthetic.main.activity_main.*
import com.example.aboutme.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

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

        binding.done_button.setOnClickListener{
            addNickname(it)
        }
    }

    private fun addNickname(view: View) {


        binding.apply{
            nickname_text.text = binding.nickname_edit.text
            invalidateAll()
            nickname_edit.visibility = View.GONE
            done_button.visibility = View.GONE
            nickname_text.visibility = View.VISIBLE
        }



        //Hide the Keyboard

        val inn = getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
        inn.hideSoftInputFromWindow(view.windowToken, 0)

    }
}

无论如何，我在尝试构建 gradle 时遇到错误。我想试试看。

Compilation Error

我是 Android 的新手。

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"

tools:context=".MainActivity">

        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        >


    <TextView
            android:text="@string/name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/textView"
            style="@style/name_style"/>
    <ImageView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:srcCompat="@android:drawable/btn_star_big_on"
            android:id="@+id/imageView2"/>
    <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:ems="10"
            android:id="@+id/nickname_edit" style="@style/name_style" android:hint="what is your nickname"/>
    <Button
            android:text="Done"
            android:layout_gravity="center_horizontal"
            style="@style/Widget.AppCompat.Button.Colored"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" android:id="@+id/done_button"/>
    <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content" android:id="@+id/nickname_text" style="@style/name_style"
            android:visibility="gone"/>
    <ScrollView
            android:id="@+id/bio_scroll"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        <TextView
                style="@style/name_style"
                android:text="@string/bio"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/bio_text"
                android:lineSpacingMultiplier="1.2"
        />
    </ScrollView>

</LinearLayout>
</layout>

error in log

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
public val Activity.done_button: Button! defined in kotlinx.android.synthetic.main.activity_main
public val Dialog.done_button: Button! defined in kotlinx.android.synthetic.main.activity_main
public val android.app.Fragment.done_button: Button! defined in kotlinx.android.synthetic.main.activity_main
public val android.support.v4.app.Fragment.done_button: Button! defined in kotlinx.android.synthetic.main.activity_main 
Unresolved reference: it    
Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
public val Activity.nickname_edit: EditText! defined in kotlinx.android.synthetic.main.activity_main
public val Dialog.nickname_edit: EditText! defined in kotlinx.android.synthetic.main.activity_main
public val android.app.Fragment.nickname_edit: EditText! defined in kotlinx.android.synthetic.main.activity_main
public val android.support.v4.app.Fragment.nickname_edit: EditText! defined in kotlinx.android.synthetic.main.activity_main

> Task :app:buildInfoGeneratorDebug

Answer 1

1) You need to add distributionUrl in gradle.wrapper-properties for latest android studio version. Your URL must be

distributionUrl=https://services.gradle.org/distributions/gradle-5.1.1-all.zip

2) 数据绑定依赖in-app级别Gradle文件

kapt 'com.android.databinding:compiler:3.1.0'

并添加

apply plugin: 'kotlin-kapt'

3) 添加 kotlin Gradle 插件项目级别 Gradle 依赖项。

dependencies {
    classpath 'com.android.tools.build:gradle:3.4.1'
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.31"
    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
}

完成上述所有操作后，只需清理、构建和重建项目即可。

Answer 2

将名称空间声明移至您的布局标记，并删除重复项。进行更改后应该如下所示：

<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"
        tools:context=".MainActivity">
    <LinearLayout
            android:orientation="vertical"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
...

之后，确保清理并重建您的项目。

kotlin 应用程序中的 DataBinding 出错

Having an error in DataBinding in kotlin app

android

kotlin

android-databinding