你需要引入插件

请将 viewBinding 元素添加到其 build.gradle 文件中

  1. apply plugin: 'com.android.application'
  2. apply plugin: 'kotlin-android'
  3. apply plugin: 'kotlin-android-extensions'
  5. android {
  6.     compileSdkVersion 29
  7.     buildToolsVersion "29.0.3"
  9.       //视图绑定插件
  10.       viewBinding {
  11.         enabled = true
  12.     }
  14.     defaultConfig {
  15.         applicationId "com.example.viewbinding"
  16.         minSdkVersion 16
  17.         targetSdkVersion 29
  18.         versionCode 1
  19.         versionName "1.0"
  21.         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
  22.     }
  24.     buildTypes {
  25.         release {
  26.             minifyEnabled false
  27.             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
  28.         }
  29.     }
  31. }
  33. dependencies {
  34.     implementation fileTree(dir: 'libs', include: ['*.jar'])
  35.     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
  36.     implementation 'androidx.appcompat:appcompat:1.1.0'
  37.     implementation 'androidx.core:core-ktx:1.2.0'
  38.     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
  39.     testImplementation 'junit:junit:4.12'
  40.     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
  41.     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
  42. }

第一种情况在Activit中使用

  1. package com.example.viewbinding
  3. import androidx.appcompat.app.AppCompatActivity
  4. import android.os.Bundle
  5. import android.os.PersistableBundle
  6. import com.example.viewbinding.databinding.ActivityMainBinding
  8. class MainActivity : AppCompatActivity() {
  9. //    声明变量
  10.     private lateinit var binding: ActivityMainBinding
  11.     override fun onCreate(savedInstanceState: Bundle?) {
  12.         super.onCreate(savedInstanceState)
  13. //        接入插件
  14.         binding = ActivityMainBinding.inflate(layoutInflater)
  15.         setContentView(binding.root)
  16.     }
  18.     override fun onStart() {
  19.         super.onStart()
  20. //        视图绑定
  21.         binding.tit1.text = "activity视图绑定"
  23. //        事件绑定
  24.         binding.button.setOnClickListener({
  25.             binding.tit1.text = "事件绑定"
  26.         })
  27.     }
  29. }

在Fragment中使用

package com.example.viewbinding

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.example.viewbinding.databinding.FragmentBlankBinding

/**
 * A simple [Fragment] subclass.
 */
class BlankFragment : Fragment() {
    private lateinit var binding: FragmentBlankBinding
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        binding = FragmentBlankBinding.inflate(layoutInflater)
        return  binding.root
//        return inflater.inflate(R.layout.fragment_blank, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
//        视图绑定
        binding.textView.text = "Fragment视图数据绑定"
//        事件绑定
        binding.button2.setOnClickListener({
            binding.textView.text = "fragment中事件绑定"
        })
    }

}

结语

后面的findViewById不用看，也不用学了。视图绑定是比较好的了