数据绑定不能与 Kotlin 中的视图绑定一起使用

Question

Android Studio 3.6

build.gradle:

buildscript {
    ext.kotlin_version = '1.3.50'
    repositories {
        google()
        jcenter()

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.6.0-beta01'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

在 app/build.gradle:

android {
    viewBinding.enabled = true
    dataBinding {
        enabled = true
    }

在我的 activity:

import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity
import androidx.viewpager2.widget.ViewPager2

import com.myproject.BuildConfig
import com.myproject.R
import com.myproject.adapter.CustomFragmentStateAdapter
import com.myproject.databinding.QrBluetoothSwipeActivityBinding
import com.myproject.ui.fragment.BluetoothPageFragment
import com.myproject.ui.fragment.QrPageFragment
import androidx.databinding.DataBindingUtil
import androidx.databinding.ObservableInt

class QRBluetoothSwipeActivity : AppCompatActivity() {
    private lateinit var viewBinding: QrBluetoothSwipeActivityBinding
    var positionObservable = ObservableInt()

    companion object {
        private val TAG = QRBluetoothSwipeActivity::class.java.name
    }

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

         // databinding init
        val binding = DataBindingUtil.setContentView<QrBluetoothSwipeActivityBinding>(
            this, R.layout.qr_bluetooth_swipe_activity
        )
        binding.setHandler(this)

        // viewbinding init
        viewBinding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)
        setContentView(viewBinding.root)

        init()
    }

 private fun init() {
        val customFragmentStateAdapter = CustomFragmentStateAdapter(this)
        customFragmentStateAdapter.addFragment(QrPageFragment())
        customFragmentStateAdapter.addFragment(BluetoothPageFragment())
        viewBinding.viewPager2.adapter = customFragmentStateAdapter

        viewBinding.viewPager2.registerOnPageChangeCallback(object :
            ViewPager2.OnPageChangeCallback() {
            override fun onPageSelected(position: Int) {
                if (BuildConfig.DEBUG) {
                    Log.d(TAG, "registerOnPageChangeCallback: position = $position")
                }
                positionObservable.set(position)
            }
        })
    }

我的qr_bluetooth_swipe_activity.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">

    <data>

        <import type="android.view.View" />

        <variable
            name="handler"
            type="com.myproject.actviity.QRBluetoothSwipeActivity" />

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.viewpager2.widget.ViewPager2
            android:id="@+id/viewPager2"
            android:layout_width="0dp"
            android:layout_height="0dp"
            app:layout_constraintBottom_toTopOf="@+id/bottonContainer"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.ConstraintLayout
            android:id="@+id/bottonContainer"
            android:layout_width="0dp"
            android:layout_height="104dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent">

            <androidx.constraintlayout.widget.ConstraintLayout
                android:id="@+id/qrBottonMainContainer"
                android:layout_width="0dp"
                android:layout_height="104dp"
                android:visibility="@{handler.positionObservable == 0 ? View.GONE: View.VISIBLE}"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"/>

启动app后滑动成功viewpager2。结果成功显示下一条消息：

10-25 14:25:24.991 D/com.myproject.actviity.QRBluetoothSwipeActivity(23012): registerOnPageChangeCallback: position = 0

不错。但是qrBottonMainContainer躲不开。为什么？

P.S。如果我删除这个：

viewBinding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)
setContentView(viewBinding.root)

然后成功工作。

为什么？

Answer 1

您不能在同一布局中同时使用它们。

ViewBinding 是 DataBinding 的一个子集，如果您想替换 ButterKnife、KotterKnife 或 KAE（Kotlin Android 扩展）但不想投资于数据绑定重构。

如果您使用 DataBinding，您已经在 binding 对象中拥有构成布局的视图的 ID 引用。类似于 binding.myTextView.

记住：

The data binding library only processes data binding layouts created using the <layout> tag.

View binding doesn't support layout variables or layout expressions, so it can't be used to bind layouts with data in XML.

根据文档here

PS：在您的特定情况下，您不能将 <layout> 标签与 ViewBinding

一起使用

Answer 2

此处解决方案没有 viewbinding

android {
    dataBinding {
        enabled = true
    }

在activity中：

     import android.os.Bundle
        import android.util.Log
        import androidx.appcompat.app.AppCompatActivity
        import androidx.viewpager2.widget.ViewPager2

        import com.myproject.BuildConfig
        import com.myproject.R
        import com.myproject.adapter.CustomFragmentStateAdapter
        import com.myproject.ui.fragment.BluetoothPageFragment
        import com.myproject.ui.fragment.QrPageFragment
        import androidx.databinding.DataBindingUtil
        import androidx.databinding.ObservableInt
        import com.myproject.databinding.QrBluetoothSwipeActivityBinding

    class QRBluetoothSwipeActivity : AppCompatActivity() {
        private lateinit var dataBinding: QrBluetoothSwipeActivityBinding
        var positionObservable = ObservableInt()

        companion object {
            private val TAG = QRBluetoothSwipeActivity::class.java.name
        }

        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            dataBinding = DataBindingUtil.setContentView<QrBluetoothSwipeActivityBinding>(
                this, R.layout.qr_bluetooth_swipe_activity
            )
            dataBinding.setHandler(this)
            init()
        }

        private fun init() {
        val customFragmentStateAdapter = CustomFragmentStateAdapter(this)
        customFragmentStateAdapter.addFragment(QrPageFragment())
        customFragmentStateAdapter.addFragment(BluetoothPageFragment())
        dataBinding.viewPager2.adapter = customFragmentStateAdapter

        dataBinding.viewPager2.registerOnPageChangeCallback(object :
            ViewPager2.OnPageChangeCallback() {
            override fun onPageSelected(position: Int) {
                if (BuildConfig.DEBUG) {
                    Log.d(TAG, "registerOnPageChangeCallback: position = $position")
                }
                positionObservable.set(position)
            }
        })
    }
}

现在 仅适用于数据绑定。

不错。

感谢@MatPag

Answer 3

如果您想在单个布局中同时使用视图绑定和数据绑定您只需要使用数据绑定，因为视图绑定是数据绑定的子集数据绑定提供视图绑定的功能。

两者的区别在于视图绑定仅用于视图引用而不用于与数据源绑定UI。

android {
buildFeatures {
    dataBinding true
  }
}




   <layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
    <variable
        name="viewmodel"
        type="com.myapp.data.ViewModel" />
</data>

</layout>




val dataBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
dataBinding.executePendingBindings()
dataBinding.tvName.text="View Binding"

数据绑定不能与 Kotlin 中的视图绑定一起使用

Databinding not work together with viewbinding in Kotlin

android

kotlin

android-viewbinder

android-databinding