It should be so simple. Databinding and viewbinding

Preface

First of all, I wish my friends a happy new year ,2020 An extraordinary year ,2021 It's a new starting point for you and me .

2021 New signature ： Code is more than , The article keeps on .

2021 The first article is right 2020 The last article at the end of the year Kotlin The end of the plug-in ,ViewBinding The rise of A supplement to .

Previous articles Kotlin The end of the plug-in ,ViewBinding The rise of This paper introduces the in Google Why is it not recommended to use Kotlin Synthesis method （Synthetic View ）, Google It is recommended to use ViewBinding Replace Kotlin Synthesis method , that ViewBinding and DataBinding What's the difference .

ViewBinding：

• Only binding is supported View
• There is no need to add... To the layout file layout label
• At the module level build.gradle Add... To the file viewBinding = true You can use
• Efficiency is higher than DataBinding, Because it avoids the overhead and performance problems associated with data binding
• Compared with kotlin-android-extensions The plug-in avoids null exceptions

DataBinding：

• Contains ViewBinding All functions
• At the module level build.gradle Add in file dataBinding = true And you need to add... In the layout file layout Tags can be used
• Support data and view Two way binding
• Less efficient than ViewBinding, Because the annotation processor will affect the construction time of data binding .

ViewBinding It can be realized , DataBinding Can be realized , however DataBinding The performance of the system is lower than that of the system ViewBinding,DataBinding and ViewBinding For every one of them XML File generation binding class .

R.layout.activity_main -> ActivityMainBinding
R.layout.fragment_main -> FragmentMainBinding
R.layout.dialog_app -> DialogAppBinding

stay Kotlin The end of the plug-in ,ViewBinding The rise of The article also analyzes Kotlin Problems caused by synthetic methods . Even if Kotlin There are many problems with the synthesis method , But there are still friends willing to use .

ViewBinding and DataBinding Solved so many problems for us , But why are many friends unwilling to use ViewBinding and DataBinding, Today we will analyze it from the perspective of use .

ViewBinding and DataBinding

I probably summarized ViewBinding and DataBinding All uses in different scenarios , Let's take a look at how to use .

Basic configuration

from Android Studio 3.6 Version start , Built in Gradle Plug in , There is no need to add any additional libraries to use them , But in Android Studio 3.6 and Android Studio 4.0 It is used in different ways .

// Android Studio 3.6
android {
    viewBinding {
        enabled = true
    }
    dataBinding{
        enabled = true
    }
}

// Android Studio 4.0
android {
    buildFeatures {
        dataBinding = true
        viewBinding = true
    }
}

ViewBinding Use

Because there are many scenes involved , In order to reduce the space , I only list the core parts , If you have never used it before , All we need to know here is ViewBinding The threshold ratio of Kotlin The synthesis method should be high .

Do not want to generate for a layout binding class , Add the following attributes to the root view of the layout file

<LinearLayout tools:viewBindingIgnore="true" >
</LinearLayout>

stay Activity Use in

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val binding: ActivityMainBinding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)
}

stay Fragment Use in

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
    val binding = FragmentViewBindBinding.inflate(inflater,container,false)
    return binding.root
}

stay Adapter The use of

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
    RecycleItemProductBinding.inflate(LayoutInflater.from(parent.context), parent, false)
}

stay Dialog Use in

override fun onCreate(savedInstanceState: Bundle?) {
    binding = DialogAppBinding.inflate(layoutInflater)
    setContentView(binding.root)
}

include Use of labels

include Without label merge label , Need to give include add id, Use it directly id that will do , Use as follows .

<include
    android:id="@+id/include"
    layout="@layout/layout_include_item" />
    
val binding: ActivityMainBinding = ActivityMainBinding.inflate(layoutInflater)
binding.include.includeTvTitle.setText(" Use  include  Control in layout ,  It doesn't contain  merge")

include Label tape merge label , Notice here and DataBinding The usage is different , to include add id, stay DataBinding Can be used directly in id,ViewBinding No way. ,ViewBinding The usage of is as follows .

<include layout="@layout/layout_merge_item" />

val binding: ActivityMainBinding = ActivityMainBinding.inflate(layoutInflater)
val mergeItemBinding = LayoutMergeItemBinding.bind(binding.root)
mergeItemBinding.mergeTvTitle.setText(" Use  include  Control in layout ,  contain  merge")

ViewStub Use of labels

According to practice , As of the publication of this article , stay Android Studio 4.2.0 bata 2 in , Can't be directly in ViewBinding Use... In layout ViewStub label , Only in DataBinding Layout （ belt layout label ） Use in , See issue

Because there is no authoritative data to prove , Here, I suggest you to work directly on the project Binding Try to , If there are others ViewBinding Implementation method in layout , Please leave me a message

DataBinding Use

Because there are many scenes involved , In order to reduce the space , I only list the core parts , If you have never used it before , All we need to know here is DataBinding The threshold ratio of Kotlin The synthesis method should be high .

You need to add layout label

<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout...>
    ...
    </LinearLayout
</layout>

stay Activity Use in

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

stay Fragment Use in

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
    val binding = FragmentViewBindBinding.inflate(inflater,container,false)
    binding.lifecycleOwner = this
    return binding.root
}

stay Adapter The use of

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
    val view = LayoutInflater.from(parent.context).inflate(viewType, parent, false)
    val bidning:RecycleItemProductBinding =  DataBindingUtil.bind(view) 
}

stay Dialog Use in

override fun onCreate(savedInstanceState: Bundle?) {
    binding = DataBindingUtil.inflate(LayoutInflater.from(context), R.layout.dialog_data_binding, null, false)
    setContentView(binding.root)
}

include Use of labels

include Without label merge label , Need to give include add id, Use it directly id that will do .

<include
    android:id="@+id/includeData"
    layout="@layout/layout_include_data_item"/>
    
val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
binding.includeData.includeTvTitle.setText(" Set by code  include layout  Control for ")

include Label tape merge label , Notice here and ViewBinding The usage is different , to include add id, stay DataBinding Can be used directly in , stay ViewBinding But not in the middle .

<include
    android:id="@+id/includeDataMerge"
    layout="@layout/layout_merge_data_item"/>

val binding: ActivityMainBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)
binding.includeDataMerge.mergeTvTitle.setText(" Set by code  merge layout  Control for ")

ViewStub Use of labels

to ViewStub add id, stay DataBinding Can be used directly in id that will do .

<ViewStub
    android:id="@+id/stub"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout="@layout/view_stub" />

binding.stub.setOnInflateListener { stub, inflated ->
    // ViewBinding
    val viewStub: ViewStubBinding = ViewStubBinding.bind(inflated)
    viewStub.tvTitle.setText(" Use  ViewStub  load  ViewBinding  Layout ")
}

binding.stub.setOnInflateListener { stub, inflated ->
    // DataBinding
    val dataViewStub: ViewStubDataBinding = DataBindingUtil.bind(inflated)!!
    dataViewStub.tvTitle.setText(" Use  ViewStub  load  DataBinding  Layout ")
}
                
if (!binding.stub.isInflated) {
    binding.stub.viewStub!!.inflate()
}   

As you can see , stay Ativity 、 Fragment 、 Dialog 、 Adapter 、 include 、 merge 、 ViewStub And so on , Use ViewBinding perhaps DataBinding Have to be handled differently , Compared with Kotlin Synthesis method , The threshold is too high .

So can you use a method , These initialization schemes can be unified , stay Kotlin You only need one line of code to realize DataBinding and ViewBinding.

One line of code

If you need to do different processing manually in each scene , This cost is very large , So I launched a new library Binding ,Binding combination Kotlin Delegate properties , Unified package DataBinding and ViewBinding Different treatments , Simple is provided API As shown below .

ViewBinding The use of

val binding: ActivityViewBindBinding by viewbind()

DataBinding The use of

val binding: ActivityDataBindBinding by databind(R.layout.activity_data_bind)
 perhaps 
val binding: ActivityDataBindBinding by databind()

As you can see , Just a few simple API All the above scenarios can be realized , Let's introduce Binding.

Binding Future planning provides a common findViewById Solution , Due to the iterative update of technology, from butterknife 、 DataBinding 、 Kotlin Synthesis method （Synthetic View ） Up to now ViewBinding , There may also be new technologies in the future , No matter how the technology changes , as long as Binding External use remains unchanged , Just update Binding , You can complete the migration .

Binding Has the following advantages ：

• Many practical cases are provided, including Ativity 、 Fragment 、 Dialog 、 Adapter 、 include 、 merge 、 ViewStub 、 Navigation 、 Data bidirectional binding Scenes, etc.
• ordinary API It takes only one line of code to achieve DataBinding perhaps ViewBinding
• Support in Activity 、AppCompatActivity 、FragmentActivity 、Fragment 、Dialog The use of DataBinding perhaps ViewBinding
• Support in ListAdapter 、 PagedListAdapter 、 PagingDataAdapter 、 RecyclerView.Adapter The use of DataBinding perhaps ViewBinding
• Support in Navigaion Fragment Management framework 、 BottomSheetDialogFragment And so on DataBinding and ViewBinding
• Avoid a lot of template code
• Avoid memory leaks , Life cycle awareness , When the life cycle is in onDestroyed() The data will be automatically destroyed

Next, let's analyze how to use Binding, Add the following code at the module level build.gradle In the file , And it needs to be turned on DataBinding perhaps ViewBinding.

dependencies {
    implementation 'com.hi-dhl:binding:1.0.7'
}

stay Activity 、AppCompatActivity 、FragmentActivity Use in , add to by viewbind() perhaps by databind(R.layout.activity_main) that will do , An example is shown below .

class MainActivity : AppCompatActivity() {

    // DataBinding
    val binding: ActivityMainBinding by databind(R.layout.activity_main)
    
    // ViewBinding
    val binding: ActivityMainBinding by viewbind()
}

stay Fragment There are two ways ：

• Mode one ： stay onCreateView Use in , This method applies to all uses Fragment Scene
• Mode two ： stay onViewCreated Use in

Mode one ：

class FragmentNav1 : Fragment(R.layout.fragment_main) {
    
    // DataBinding
  	val binding: FragmentMainBinding by databind()
    
    // ViewBinding
  	 val binding: FragmentMainBinding by viewbind()
  
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        return binding.root
    }
}

Mode two , The following points need to be noted ：

• Can't be in Navigaion Fragment and BottomSheetDialogFragment Use in
• Among others Fragment Scene , If you use Mode two The interface does not display , change to the use of sth. Mode one Can solve

class FragmentNav1 : Fragment(R.layout.fragment_main) {
    
    // DataBinding
  	val binding: FragmentMainBinding by databind()
    
    // ViewBinding
  	 val binding: FragmentMainBinding by viewbind()
  
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding.apply { textView.setText("Binding") }
    }
}

stay Dialog The method of use in is as follows .

class AppDialog(context: Context) : Dialog(context, R.style.AppDialog) {

    // DataBinding
    val binding: DialogAppBinding by databind(R.layout.dialog_data_binding)
    
    // ViewBinding
    val binding: DialogAppBinding by viewbind()
}

Or add life cycle aware Dialog.

class AppDialog(context: Context,lifecycle: Lifecycle) : Dialog(context, R.style.AppDialog) {

    // DataBinding  Monitor life cycle 
    val binding: DialogAppBinding by databind(R.layout.dialog_data_binding, lifecycle)
    
    // ViewBinding  Monitor life cycle 
    val binding: DialogAppBinding by viewbind(lifecycle)
    
}

stay Adapter Use in DataBinding and ViewBinding, Only need ViewHolder Add by viewbind() perhaps by databind() that will do , An example is shown below .

class ProductViewHolder(view: View) : RecyclerView.ViewHolder(view) {
    
    // DataBinding
    val binding: RecycleItemProductBinding by databind()

    // ViewBinding
    val binding: RecycleItemProductHeaderBinding by viewbind()

}

Extension method , Support DataBinding Bind data during initialization .

val binding: ActivityDataBindBinding by databind(R.layout.activity_data_bind) {
    val account = Account()
    account.name = "test"
    this.account = account
}

The above is just a few common usages , Of course, there are more practical cases （include 、 merge 、 ViewStub 、 Navigation 、 Data bidirectional binding wait ） It has been uploaded to GitHub Welcome to the warehouse Binding see .

GitHub Warehouse : https://github.com/hi-dhl/Binding

This article can be understood as a review of the previous article Kotlin The end of the plug-in ,ViewBinding The rise of A supplement to , From the perspective of use DataBinding and ViewBinding The difference , At the same time, it also introduces how to realize in a simpler way DataBinding and ViewBinding.

This is the end of the article , If it helps Point a praise Is the biggest encouragement to me

Code is more than , The article keeps on

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