Kotlin: RecyclerView 使用

基本使用

//设置布局管理器
recyclerView.layoutManager =LinearLayoutManager(this);
//设置adapter
recyclerView.adapter =  myAdapter(this);   
// 设置分割线
recyclerView.addItemDecoration(Decoration());
// 设置 item 增加 移除动画
recyclerView.itemAnimator = itemAnimator();
// 设置item 固定高度
recyclerView.setHasFixedSize(true);

• Activity

package com.example.lijiangbing.recyclerviewdemo

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v7.widget.GridLayoutManager
import android.support.v7.widget.LinearLayoutManager
import android.support.v7.widget.RecyclerView
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import com.example.lijiangbing.recyclerviewdemo.R.id.id_recyclerView
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.cell.view.*

class MainActivity : AppCompatActivity(),RecyclerItemClickListenner {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        id_recyclerView.layoutManager = LinearLayoutManager(this);
        // adapter 构造函数
        id_recyclerView.adapter =  myAdapter(this, initData());
        id_recyclerView.setHasFixedSize(true);
    }

    // item 点击回调
    override fun onRecyclerViewItemClick(view: View, position: Int) {
        Log.e("view----:$view","position----:$position")
    }
}

// 简单数据源
fun initData():ArrayList<String>{
    var mDatas: ArrayList<String> = arrayListOf();
    var i: Char = 'A';
    while (i < 'Z'){
        mDatas.add(i.toString());
        i ++;
    }
    return mDatas;
}

• 点击回调接口:RecyclerItemClickListenner

package com.example.lijiangbing.recyclerviewdemo
import android.view.View

interface RecyclerItemClickListenner {
    fun onRecyclerViewItemClick(view: View, position: Int);
}

• myAdapter

// 定义构造方法
class myAdapter(val mOnItemClickLitener: RecyclerItemClickListenner?,val mDatas: ArrayList<String>): RecyclerView.Adapter<myAdapter.myHolderView>(){

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): myHolderView {

         return myHolderView(LayoutInflater.from(parent?.context).inflate(R.layout.cell,parent,false))
    }

    override fun onBindViewHolder(holder: myHolderView?, position: Int) {

        holder?.tv?.text = mDatas.get(position);
  // item 点击回调
        mOnItemClickLitener?.let {
            holder?.itemView?.setOnClickListener {
                mOnItemClickLitener.onRecyclerViewItemClick(holder?.itemView,position);
            }
        }
    }

    override fun getItemCount(): Int {
        return mDatas.count();

    }

     class myHolderView(view: View): RecyclerView.ViewHolder(view){
        val tv: TextView;
        init {
            tv = view.cell_textView
        }

    }


}

• activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context="com.example.lijiangbing.recyclerviewdemo.MainActivity">
    
    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"></android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>

• item 布局文件

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

    xmlns:app="http://schemas.android.com/apk/res-auto">


    <View
        android:id="@+id/cell_view"
        android:background="#3E3"
        android:layout_width="match_parent"
        android:layout_height="60dp" />

    <TextView
        android:id="@+id/cell_textView"
        android:layout_width="match_parent"
        android:layout_height="44dp"
        android:background="#FFFFFF"
        android:textAlignment="center"
        android:paddingVertical="13dp"
        app:layout_constraintTop_toTopOf="@id/cell_view"
        app:layout_constraintStart_toStartOf="@id/cell_view"
        />
</android.support.constraint.ConstraintLayout>

简单的CreyclerView 就完成了;
记录一下导入CreyclerView 架包时犯得错:
导入方法:

File -> project Structure ->app ->  dependencies 
add "com.android.support:com.android.support:recyclerview-v7:26.0.0-beta1"

查看Project 下 External Libraries 发现 "com.android.support:recyclerview-v7:26.0.0-beta1" 已经有了,大概率可以直接使用了,然而 .......还是出错了,没有log 信息,就是运行不起来

仔细看了看dependencies{} 问题就来了: appcompat竟然是 25.x.x
升级appcompat 到v7:26.0.0-beta1即可:
implementation 'com.android.support:appcompat-v7:26.0.0-beta1'