package com.example.baseadapter;

import android.os.Bundle;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Adapter;
import android.widget.ListView;

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

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        List<itemBean> ItemBeanList=new ArrayList<>();
        for(int i=0;i<20;i++){
            ItemBeanList.add(new itemBean(
                    R.mipmap.ic_launcher,
                    "标题"+i,
                    "内容"+i
            ));
        }
        ListView listView=findViewById(R.id.lv_main);
        listView.setAdapter(new MyAdapater(this,ItemBeanList));
    }

}

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

    <ImageView
        android:layout_width="wrap_content"
        android:src="@mipmap/ic_launcher"
        android:id="@+id/iv_image"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="10dp"
        android:layout_height="wrap_content"/>

    <TextView
        android:layout_width="match_parent"
        android:text="标题"
        android:textSize="30sp"
        android:id="@+id/tv_title"
        android:layout_toRightOf="@id/iv_image"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="10dp"
        android:gravity="center_horizontal"
        android:layout_height="wrap_content"/>

    <TextView
        android:layout_width="match_parent"
        android:text="Content"
        android:id="@+id/tv_content"
        android:textSize="20sp"
        android:layout_toRightOf="@id/iv_image"
        android:layout_below="@id/tv_title"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_height="wrap_content"/>


</RelativeLayout>

package com.example.baseadapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

public class MyAdapater extends BaseAdapter {

    private List<itemBean> mList;
    private LayoutInflater mInflater;

    public MyAdapater(Context context, List<itemBean> itemBeanList) {
        mList = itemBeanList;
        mInflater = LayoutInflater.from(context);
    }

    @Override
    //返回适配器中数据集中数据的个数
    public int getCount() {
        return mList.size();
    }

    @Override
    //获取数据集中与指定索引对应的数据项
    public Object getItem(int position) {
        return mList.get(position);
    }

    @Override
    //获取指定行对应的ID
    public long getItemId(int position) {
        return position;
    }

    @Override
    //获取每个Item的显示内容
    public View getView(int position, View convertView, ViewGroup parent) {

        //*****************逗比式*****************************↓
        //没有任何的优化处理，每次都新建一个view，效率低下

        /*View view = mInflater.inflate(R.layout.item_layout, null);//第一个参数，需要装载到item中的布局文件；第二个参数，一般填null
        ImageView imageView = view.findViewById(R.id.iv_image);
        TextView title = view.findViewById(R.id.tv_title);
        TextView content=view.findViewById(R.id.tv_content);
        itemBean bean=mList.get(position);

        imageView.setImageResource(bean.ItemImageReId);
        title.setText(bean.ItemTitle);
        content.setText(bean.ItemContent);
        return view;*/
        //*****************逗比式*****************************↑

        //*****************普通式*****************************↓
        //大量的findViewById耗费时间

        /*if(convertView==null){//为空，缓冲池里没有缓存，避免了重复创建
            convertView=mInflater.inflate(R.layout.item_layout,null);
        }

        ImageView imageView = convertView.findViewById(R.id.iv_image);
        TextView title = convertView.findViewById(R.id.tv_title);
        TextView content=convertView.findViewById(R.id.tv_content);
        itemBean bean=mList.get(position);
        imageView.setImageResource(bean.ItemImageReId);
        title.setText(bean.ItemTitle);
        content.setText(bean.ItemContent);
        return convertView;*/
        //*****************普通式*****************************↑

        //*****************文艺式*****************************↓
        //不仅利用了缓存，并且通过ViewHolder类来减少了FindViewById在时间上的浪费

        ViewHolder viewHolder;

        if(convertView==null){//为空，缓冲池里没有缓存
            viewHolder=new ViewHolder();
            convertView=mInflater.inflate(R.layout.item_layout,null);
            viewHolder.imageView=convertView.findViewById(R.id.iv_image);
            viewHolder.title=convertView.findViewById(R.id.tv_title);
            viewHolder.content=convertView.findViewById(R.id.tv_content);
            convertView.setTag(viewHolder);
            //通过setTag将ViewHolder与ConvertView关联
        }
        else {
            viewHolder = (ViewHolder) convertView.getTag();
            itemBean bean=mList.get(position);
            viewHolder.imageView.setImageResource(bean.ItemImageReId);
            viewHolder.title.setText(bean.ItemTitle);
            viewHolder.content.setText(bean.ItemContent);
        }
        return convertView;
        //*****************文艺式*****************************↑

    }
    //创建内部类ViewHolder
    class ViewHolder{
        public ImageView imageView;
        public TextView title;
        public TextView content;
    }

}

package com.example.baseadapter;

public class itemBean {
    public int ItemImageReId;
    public String ItemTitle;
    public String ItemContent;


    public itemBean(int itemImageReId, String itemTitle, String itemContent) {
        ItemImageReId = itemImageReId;
        ItemTitle = itemTitle;
        ItemContent = itemContent;
    }

}