recycleview 的 ItemView常用验证

最新推荐文章于 2024-04-14 01:40:16 发布

原创最新推荐文章于 2024-04-14 01:40:16 发布 · 510 阅读

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#holder

本文通过实例详细解析了Android中RecyclerView的实现原理，包括Item布局、适配器代码及Activity的编写方式，并通过日志输出展示了ViewHolder的创建、复用过程。

引用：


dependencies {
...
    compile 'com.android.support:recyclerview-v7:25.3.1'
}

代码：
1、item布局

<?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="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/id_num"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="#ff5500"
        android:gravity="center"
        android:text="hello" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorPrimary" />

</LinearLayout>

2、适配器代码

package com.example.lihui.testrecycleview;

import android.content.Context;
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 java.util.List;

/**
 * Created by lihui on 2017/8/22.
 */

public class MyRecyclerAdapter extends RecyclerView.Adapter<MyRecyclerAdapter.MyViewHolder> {
    private static final String TAG = "MyRecyclerAdapter";

    private List<String> mData;
    private Context mContext;
    private LayoutInflater inflater;

    public MyRecyclerAdapter(Context context, List<String> data) {
        this.mContext = context;
        this.mData = data;
        inflater = LayoutInflater.from(mContext);
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    @Override
    public void onViewRecycled(MyViewHolder holder) {
        super.onViewRecycled(holder);
        Log.d(TAG, "onViewRecycled: " + holder.tv.getText().toString() + ", position: " + holder.getAdapterPosition());
    }

    //填充onCreateViewHolder方法返回的holder中的控件
    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position) {
        Log.d(TAG, "onBindViewHolder: 验证是否重用了");
        Log.d(TAG, "onBindViewHolder: 重用了" + holder.tv.getTag());
        Log.d(TAG, "onBindViewHolder: 放到了" + mData.get(position));
        holder.tv.setText(mData.get(position));
        holder.tv.setTag(mData.get(position));
    }

    //重写onCreateViewHolder方法，返回一个自定义的ViewHolder
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        Log.d(TAG, "onCreateViewHolder");
        View view = inflater.inflate(R.layout.item_layout, parent, false);
        return new MyViewHolder(view);
    }

    static class MyViewHolder extends RecyclerView.ViewHolder {

        TextView tv;

        public MyViewHolder(View view) {
            super(view);
            tv = (TextView) view.findViewById(R.id.id_num);
        }
    }
}

3、activity代码

package com.example.lihui.testrecycleview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private List<String> mData;
    private MyRecyclerAdapter recycleAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        recyclerView = (RecyclerView) findViewById(R.id.id_recyclerView);
        initData();
        recycleAdapter = new MyRecyclerAdapter(MainActivity.this, mData);
        //设置布局管理器 , 将布局设置成纵向
        LinearLayoutManager linerLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
        recyclerView.setLayoutManager(linerLayoutManager);        // ...
        recyclerView.setAdapter(recycleAdapter);
        // ...
    }

    private void initData() {
        mData = new ArrayList<>();
        mData.add("test1"); //0
        mData.add("test2"); //0
        mData.add("test3"); //0
        mData.add("test4"); //0
        mData.add("test5"); //0
        mData.add("test6"); //0
        mData.add("test7"); //0
        mData.add("test8"); //0
        mData.add("test9"); //0
        mData.add("test10"); //0
        mData.add("test11"); //0
        mData.add("test12"); //0
        mData.add("test13"); //0
        mData.add("test14"); //0

    }
}

4、recycleview 布局

<?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"
    tools:context="com.example.lihui.testrecycleview.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

log打印：

08-22 23:08:25.601 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:08:25.604 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:08:25.604 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:08:25.604 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test1
08-22 23:08:25.605 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:08:25.608 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:08:25.608 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:08:25.608 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test2
08-22 23:08:25.608 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:08:25.609 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:08:25.609 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:08:25.609 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test3
08-22 23:08:25.610 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:08:25.611 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:08:25.611 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:08:25.611 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test4
08-22 23:08:25.611 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:08:25.614 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:08:25.614 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:08:25.614 10929-10929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test5

1、手机一屏显示5条

往上滑动：

08-22 23:18:19.953 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:19.956 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:19.956 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:19.956 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test1
08-22 23:18:19.956 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:19.965 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:19.965 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:19.965 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test2
08-22 23:18:19.972 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:19.973 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:19.973 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:19.973 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test3
08-22 23:18:19.973 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:19.974 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:19.974 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:19.974 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test4
08-22 23:18:19.975 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:19.976 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:19.976 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:19.976 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test5
08-22 23:18:28.460 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:28.467 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:28.467 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:28.467 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test6
08-22 23:18:40.344 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:40.352 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:40.352 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:40.352 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test7
08-22 23:18:45.058 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:45.065 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:45.065 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:45.065 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test8
08-22 23:18:47.950 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onCreateViewHolder
08-22 23:18:47.955 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:47.955 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了null
08-22 23:18:47.955 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test9
08-22 23:18:48.658 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test1, position: 0
08-22 23:18:51.126 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了

***********************************************************
08-22 23:18:51.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test1
***********************************************************
08-22 23:18:51.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test10

从第10个开始重用（第一个）
08-22 23:18:48.658 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test1, position: 0
08-22 23:18:51.126 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:18:51.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test1
08-22 23:18:51.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test10
08-22 23:20:53.751 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test2, position: 1

                                                                                      [ 08-22 23:20:53.782 27800:27800 I/         ]
                                                                                      power log dlsym ok
08-22 23:20:53.838 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:20:53.838 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test2
08-22 23:20:53.838 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test11
08-22 23:20:54.528 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test3, position: 2
08-22 23:20:55.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:20:55.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test3
08-22 23:20:55.127 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test12
08-22 23:20:55.140 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test4, position: 3
08-22 23:21:00.171 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:21:00.171 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test4
08-22 23:21:00.171 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test13
08-22 23:21:00.351 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test5, position: 4
08-22 23:21:00.667 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 验证是否重用了
08-22 23:21:00.667 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 重用了test5
08-22 23:21:00.667 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onBindViewHolder: 放到了test14
08-22 23:21:01.027 18929-18929/com.example.lihui.testrecycleview D/MyRecyclerAdapter: onViewRecycled: test6, position: 5

研究发现，具体从哪一个开始重用不确定！！！！内部已经实现了，算法什么样子，我们不需要知道！！！