【Android Studio】安卓开发初体验——RecycleView的使用

RecycleView简介

增强版的ListView

能够实现横向滚动

RecyclerView是support-v7包中的新组件

是一个强大的滑动组件

与经典的ListView相比，同样拥有item回收复用的功能

RecyclerView封装了viewholder的回收复用

也就是说RecyclerView标准化了ViewHolder

编写Adapter面向的是ViewHolder

提供了一种插拔式的体验，高度的解耦

可以控制Item增删的动画，可以通过ItemAnimator这个类进行控制

样例效果

实现图书列表，点击一个图书，可查看详细图书信息

实现过程

1. 添加库引用

在build.gradle文件中添加依赖

dependencies {
　　implementation 'androidx.recyclerview:recyclerview:1.1.0'
}

2. 布局使用RecycleView控件

拉入一个recyclerView

或是直接编辑代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

　　

3. 自定义适配器Adapter

创建一个book_item.xml作为每一本书籍的显示格式

其内容为

 

创建一个Book书籍类

package com.example.myapplication3

class Book(val name: String, val imageId: Int, val intro: String) {
}

创建一个BookAdapter适配器

4. 实现内部类ViewHolder

class BookAdapter(val bookList: List<Book>):
    RecyclerView.Adapter<BookAdapter.ViewHolder>(){

    inner class ViewHolder(view: View):
      RecyclerView.ViewHolder(view){
        val bookImage: ImageView = view.findViewById(R.id.book_image)
        val bookName: TextView = view.findViewById(R.id.book_name)
        val bookIntro: TextView = view.findViewById(R.id.book_intro)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
  
    }
    override fun getItemCount(): Int {
　　}

}

　　

5. 实现3个方法

在onBindViewHolder中实现页面的跳转

使用intent的putExtra字符串数据

   override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.book_item, parent, false)
        val viewHolder = ViewHolder(view)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val book = bookList[position]
        holder.bookImage.setImageResource(book.imageId)
        holder.bookName.text = book.name
        holder.bookIntro.text = book.intro
        holder.itemView.setOnClickListener{

            val position = holder.adapterPosition
            val book = bookList[position]
            val intent = Intent(holder.itemView.context, DetailActivity::class.java)
            intent.putExtra("book_imageId", book.imageId.toString())
            intent.putExtra("book_name", book.name)
            intent.putExtra("book_intro", book.intro)
            holder.itemView.context.startActivity(intent)
        }
        holder.bookImage.setOnClickListener{
            //同上holder.itemView.setOnListener内容
        }
    }
    override fun getItemCount(): Int = bookList.size

　　

6. 使用布局和适配器

主页代码

MainActivity.kt

package com.example.myapplication3

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    private val BookList = ArrayList<Book>()
    private val bookImageIds = intArrayOf(
        R.drawable.book1,
        R.drawable.book2, R.drawable.book3,
        R.drawable.book4, R.drawable.book5,
        R.drawable.book6, R.drawable.book7,
        R.drawable.book8, R.drawable.book9,
        R.drawable.book10
    )
    private val bookNames = arrayOf(
        "Java编程思想", "程序员修炼之道", "零基础入门学习Python", "Java从入门到精通"
        , "深入理解Java虚拟机", "算法导论", "Android开发艺术探索", "Android进阶之光"
        , "疯狂安卓讲义", "Android开发从入门到精通"
    )
    private val bookIntros = arrayOf(
        "Java编程思想", "程序员修炼之道", "零基础入门学习Python", "Java从入门到精通"
        , "深入理解Java虚拟机", "算法导论", "Android开发艺术探索", "Android进阶之光"
        , "疯狂安卓讲义", "Android开发从入门到精通"
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        init()
        val layoutManager = LinearLayoutManager(this)
        recyclerView.layoutManager = layoutManager
        val adapter = BookAdapter(BookList)
        recyclerView.adapter = adapter
    }

    fun init(){
        for(i in 0 until bookNames.size){
            val book = Book(bookNames[i], bookImageIds[i], bookIntros[i])
            BookList.add(book)
        }
    }
}

详细页代码

DetailActivity.kt

使用intent的getStringExtra方法获取上一页数据

注意数据名称要

package com.example.myapplication3

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_detail.*

class DetailActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_detail)

        val name = intent.getStringExtra("book_name")
        val intro = intent.getStringExtra("book_intro")
        val imageId = intent.getStringExtra("book_imageId").toInt()
        imageView.setImageResource(imageId)
        book_introView.text = intro
        book_nameView.text = name
    }
}

详情页布局随意

activity_detail.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".DetailActivity">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="horizontal">

        <LinearLayout

            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="5dp"
            android:orientation="vertical">

            <TextView
                android:id="@+id/book_nameView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="TextView"
                android:textSize="18sp"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/book_introView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="TextView" />

        </LinearLayout>

    </LinearLayout>
</LinearLayout>

　　

参考资料：

第一行代码 Android（第3版本）郭霖

GDUFE移动应用开发课程