Android RecyclerView组件的使用

官方介绍

RecyclerView是ListView的一个更高级、更灵活的版本。RecyclerView组件是为大量的视图组件提供的一种容器，使得它们可以有效的在其中循环和滚动。 RecyclerView is a more advanced and flexible version of ListView. This widget is a container for large sets of views that can be recycled and scrolled very efficiently. Use the RecyclerView widget when you have lists with elements that change dynamically.

RecyclerView的使用

最终要达到的效果

如下图所示

编写相关的布局文件

MainItem布局如下：

代码语言：html复制

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="120dp"
    android:orientation="vertical">
    <ImageView
        android:id="@ id/itemIcon"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_gravity="center"
        android:layout_weight="0.7"
        tools:ignore="ContentDescription"
        tools:srcCompat="@tools:sample/avatars" />
    <TextView
        android:textSize="20sp"
        android:id="@ id/itemName"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="0.3"
        android:gravity="center" />
</LinearLayout>

实现继承自RecyclerView.Adapter的Adapter类

代码语言：java复制

class MainItemAdapter(private val itemList: List<MainItem>) :
    RecyclerView.Adapter<MainItemAdapter.ViewHolder>() {
    inner class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        val itemName: TextView = view.findViewById(R.id.itemName)
        val itemIcon: ImageView = view.findViewById(R.id.itemIcon)
    }
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val ctx = parent.context
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.main_item, parent, false)
        return ViewHolder(view).apply {
            itemView.setOnClickListener {
                val position = this.adapterPosition
                val mainItem = itemList[position]
                when (mainItem.id) {
                    1 -> {
                        ctx.startActivity(Intent(ctx, SenderActivity::class.java))
                    }
                }
            }
        }
    }
    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val mainItem = itemList[position]
        holder.itemName.text = mainItem.name
        holder.itemIcon.setImageResource(mainItem.iconId)
    }
    override fun getItemCount(): Int = itemList.size
}

在Activity中初始化数据和RecyclerView

代码语言：java复制

private val itemList = ArrayList<MainItem>()
private fun initItems() {
    repeat(20) {
        itemList.addAll(
            listOf(
                MainItem(1, "Activity演示", R.drawable.activity_icon)
            )
        )
    }
}
private fun initRecyclerView() {
    val recyclerView = findViewById<RecyclerView>(R.id.recycler_view)
    recyclerView.layoutManager = GridLayoutManager(this, 3)
    recyclerView.adapter = MainItemAdapter(itemList)
}

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