使用 Kotlin 在 Android 应用中使用 RecyclerView？

此示例演示了如何在 Android 应用中使用 Kotlin 使用 RecyclerView。

步骤 1 − 在 Android Studio 中创建一个新项目，转到文件？新建项目，并填写所有必需的详细信息以创建新项目。

步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。

示例

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/rlMain"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:layout_margin="16dp"
   android:orientation="vertical">
<androidx.recyclerview.widget.RecyclerView
   android:id="@+id/recyclerView"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />
</LinearLayout>

步骤 3 − 将以下代码添加到 src/MainActivity.kt

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.DefaultItemAnimator
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
class MainActivity : AppCompatActivity() {
   private val movieList = ArrayList<MovieModel>()
   private lateinit var moviesAdapter: MoviesAdapter
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      val recyclerView: RecyclerView = findViewById(R.id.recyclerView)
      moviesAdapter = MoviesAdapter(movieList)
      val layoutManager = LinearLayoutManager(applicationContext)
      recyclerView.layoutManager = layoutManager
      recyclerView.itemAnimator = DefaultItemAnimator()
      recyclerView.adapter = moviesAdapter
      prepareMovieData()
   }
   private fun prepareMovieData() {
      var movie = MovieModel("Mad Max: Fury Road", "Action & Adventure", "2015")
      movieList.add(movie)
      movie = MovieModel("Inside Out", "Animation, Kids & Family", "2015")
      movieList.add(movie)
      movie = MovieModel("Star Wars: Episode VII - The Force Awakens", "Action", "2015")
      movieList.add(movie)
      movie = MovieModel("Shaun the Sheep", "Animation", "2015")
      movieList.add(movie)
      movie = MovieModel("The Martian", "Science Fiction & Fantasy", "2015")
      movieList.add(movie)
      movie = MovieModel("Mission: Impossible Rogue Nation", "Action", "2015")
      movieList.add(movie)
      movie = MovieModel("Up", "Animation", "2009")
      movieList.add(movie)
      movie = MovieModel("Star Trek", "Science Fiction", "2009")
      movieList.add(movie)
      movie = MovieModel("The LEGO MovieModel", "Animation", "2014")
      movieList.add(movie)
      movie = MovieModel("Iron Man", "Action & Adventure", "2008")
      movieList.add(movie)
      movie = MovieModel("Aliens", "Science Fiction", "1986")
      movieList.add(movie)
      movie = MovieModel("Chicken Run", "Animation", "2000")
      movieList.add(movie)
      movie = MovieModel("Back to the Future", "Science Fiction", "1985")
      movieList.add(movie)
      movie = MovieModel("Raiders of the Lost Ark", "Action & Adventure", "1981")
      movieList.add(movie)
      movie = MovieModel("Goldfinger", "Action & Adventure", "1965")
      movieList.add(movie)
      movie = MovieModel("Guardians of the Galaxy", "Science Fiction & Fantasy", "2014")
      movieList.add(movie)
      moviesAdapter.notifyDataSetChanged()
   }
}

步骤 4 − 创建一个新的类 MovieModel.kt 并添加以下代码 −

class MovieModel(title: String?, genre: String?, year: String?) {
   private var title: String
   private var genre: String
   private var year: String
   init {
      this.title = title!!
      this.genre = genre!!
      this.year = year!!
   }
   fun getTitle(): String? {
      return title
   }
   fun setTitle(name: String?) {
      title = name!!
   }
   fun getYear(): String? {
      return year
   }
   fun setYear(year: String?) {
      this.year = year!!
   }
   fun getGenre(): String? {
      return genre
   }
   fun setGenre(genre: String?) {
      this.genre = genre!!
   }
}

步骤 5 − 创建一个新的类 MoviesAdapter.kt 并添加以下代码 −

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.annotation.NonNull
import androidx.recyclerview.widget.RecyclerView
internal class MoviesAdapter(private var moviesList: List<MovieModel>) :
RecyclerView.Adapter<MoviesAdapter.MyViewHolder>() {
   internal inner class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
      var title: TextView = view.findViewById(R.id.title)
      var year: TextView = view.findViewById(R.id.year)
      var genre: TextView = view.findViewById(R.id.genre)
   }
   @NonNull
   override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
      val itemView = LayoutInflater.from(parent.context)
      .inflate(R.layout.movie_list, parent, false)
      return MyViewHolder(itemView)
   }
   override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
      val movie = moviesList[position]
      holder.title.text = movie.getTitle()
      holder.genre.text = movie.getGenre()
      holder.year.text = movie.getYear()
   }
   override fun getItemCount(): Int {
      return moviesList.size
   }
}

步骤 6 − 创建一个布局资源文件 item_row.xml 并添加以下内容 −

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   android:layout_width="match_parent"
   android:layout_height="100dp"
   android:layout_margin="8dp"
   app:cardBackgroundColor="@android:color/holo_red_dark">
   <RelativeLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:padding="8dp">
   <TextView
      android:id="@+id/title"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentStart="true"
      android:layout_toStartOf="@+id/year"
      android:textColor="@android:color/white"
      android:textSize="16sp"
      android:textStyle="bold" />
   <TextView
      android:id="@+id/year"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentEnd="true"
      android:textColor="@android:color/white" />
   <TextView
      android:id="@+id/genre"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:textColor="@android:color/white" />
   </RelativeLayout>
</androidx.cardview.widget.CardView>

步骤 7 − 将以下代码添加到 androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的计算机。要从 Android Studio 运行应用程序，请打开您的一个项目活动文件并单击运行图标 工具栏中的。选择您的移动设备作为选项，然后检查您的移动设备，它将显示您的默认屏幕

更新于：2020年7月21日

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