Android : ListView + BaseAdapter-2简单应用

容器与适配器： http://t.csdnimg.cn/ZfAJ7

实体类 News.java

package com.example.mylistviewadapter2.entity;


public class News {
    private   String title;
    private  String content;
    private int img;

    public News(String title, String content, int img){
        this.title = title;
        this.content = content;
        this.img =img;
    }

    public String getTitile() {
        return title;
    }

    public void setTitile(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public int getImg() {
        return img;
    }

    public void setImg(int img) {
        this.img = img;
    }
}

适配器写个类继承BaseAdapter

package com.example.mylistviewadapter2;

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 com.example.mylistviewadapter2.entity.News;

import java.util.List;

public class NewsAdpater extends BaseAdapter {
    private List<News> date;
    private Context context;
    //两个标记类
    private  static final  int TYPE_NEWS_1 = 0;
    private  static final  int TYPE_NEWS_2 = 1;
    //構造器
    public NewsAdpater(List<News> date, Context context){
        this.date = date;
        this.context = context;
    }

    //BaseAdapter最基本的几个方法：
    // 1. getCount 填充的数据集数
    // 2.getItem 数据集中指定索引对应的数据项
    // 3. getItemId 指定行所对应的ID
    // 4. getView 每个Item所显示的类容

    @Override
    public int getCount() {
        //充的数据集数
        return date.size();
    }

    @Override
    public Object getItem(int position) {
        //数据集中指定索引对应的数据项
        return date.get(position);
    }

    @Override
    public long getItemId(int position) {
        // 指定行所对应的ID
        return position;
    }

    //重写 getItemViewType 返回对应的item布局类型
    @Override
    public int getItemViewType(int position) {
       if(position % 2 == 0){
           return TYPE_NEWS_1;
       }else{
           return TYPE_NEWS_2;
        }
    }
    //重写 getViewTypeCount 返回总共有几个item布局类型
    @Override
    public int getViewTypeCount() {
        return 2;
    }

    //优化
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        //获取布局类型
        int type = getItemViewType(position);

        ViewHoler holer = null;
        ViewHoler2 holer2 = null;
        if(convertView == null){
            switch (type){
                case TYPE_NEWS_1:
                    holer = new ViewHoler();
                    //每个Item所显示的类容
                    convertView =  LayoutInflater.from(context).inflate(R.layout.left_list_view,parent,false);
                    holer.imageView = convertView.findViewById(R.id.btnImg);
                    holer.tvTitle = convertView.findViewById(R.id.tvH);
                    holer.tbCont = convertView.findViewById(R.id.tvCont);

                    convertView.setTag(holer);
                    break;
                case TYPE_NEWS_2:
                    holer2 = new ViewHoler2();
                    //每个Item所显示的类容
                    convertView =  LayoutInflater.from(context).inflate(R.layout.right_list_view,parent,false);
                    holer2.imageView = convertView.findViewById(R.id.btnImg2);
                    holer2.tvTitle = convertView.findViewById(R.id.tvH2);
                    holer2.tbCont = convertView.findViewById(R.id.tvCont2);

                    convertView.setTag(holer2);
                    break;
            }

        }else {
            switch (type){
                case TYPE_NEWS_1:
                    holer = (ViewHoler)convertView.getTag();
                    break;
                case  TYPE_NEWS_2:
                    holer2 = (ViewHoler2)convertView.getTag();
                    break;

            }
        }

        switch (type){
            case TYPE_NEWS_1:
                //摄入值
                holer.imageView.setBackgroundResource(date.get(position).getImg());
                holer.tvTitle.setText(date.get(position).getTitile());
                holer.tbCont.setText(date.get(position).getContent());
                break;
            case TYPE_NEWS_2:
                //摄入值
                holer2.imageView.setBackgroundResource(date.get(position).getImg());
                holer2.tvTitle.setText(date.get(position).getTitile());
                holer2.tbCont.setText(date.get(position).getContent());
               break;
        }

        return convertView;
    }
    static class ViewHoler{
        ImageView imageView;
        TextView tvTitle;
        TextView tbCont;
    }

    static class ViewHoler2{
        ImageView imageView;
        TextView tvTitle;
        TextView tbCont;
    }
}

MainActivity.java

package com.example.mylistviewadapter2;

import static android.widget.Toast.LENGTH_SHORT;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

import com.example.mylistviewadapter2.entity.News;

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

public class MainActivity extends AppCompatActivity {
    //
    private ListView listView;
    private Context context;
    private List<News> listNews =null;

    //适配器
    private  NewsAdpater newsAdpater=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        context = this;

        listView = findViewById(R.id.listVi);

        listNews = new ArrayList<>();
        //传入内容
        for(int i= 0 ; i < 10; i++){
            listNews.add(new News("这是标题"+i,"我是内容我是内容我是内容我是内容我是内容我是内容我是内容"+i,R.mipmap.bg));
        }
        newsAdpater = new NewsAdpater(listNews,context);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(context, "点击了第" + position + "条数据", LENGTH_SHORT).show();
            }
        });
        //往容器设置适配器
        listView.setAdapter(newsAdpater);
    }

}

activity_main.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:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/listVi"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

left_list_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:descendantFocusability="blocksDescendants"
    android:layout_height="match_parent">
    <!--
   解决 listView.setOnItemClickListener 事件失效
1>：原因如下：
此时 在item 区域中，event（事件）的焦点被内部 View抢占了，也就是说只有 内部的View的click事件有效，而item的事件无法被触发，所以导致 点击listview的 item 时，不能响应点击事件；

2>：解决方法如下：
在 item的根布局中添加如下属性即可：
android:descendantFocusability="blocksDescendants"，表示 ViewGroup会覆盖子类控件而直接获取焦点；
    -->
    <ImageView
        android:id="@+id/btnImg"
        android:layout_width="200dp"
        android:layout_height="100dp"
        android:scaleType="fitXY"
        android:src="@mipmap/bg"
        />
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <TextView
            android:id="@+id/tvH"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="我是标题"
            android:gravity="center"
            android:textSize="16sp"
            android:textStyle="bold"
            />
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

        <TextView
            android:id="@+id/tvCont"
            android:layout_marginTop="10px"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="我是内容文本asdfasdfasdfasdfasdfasdfs"
            android:textSize="12sp"
            android:textStyle=""
            />
        </ScrollView>
    </LinearLayout>
</LinearLayout>

right_list_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:descendantFocusability="blocksDescendants"
    android:layout_height="match_parent">
    <!--
   解决 listView.setOnItemClickListener 事件失效
1>：原因如下：
此时 在item 区域中，event（事件）的焦点被内部 View抢占了，也就是说只有 内部的View的click事件有效，而item的事件无法被触发，所以导致 点击listview的 item 时，不能响应点击事件；

2>：解决方法如下：
在 item的根布局中添加如下属性即可：
android:descendantFocusability="blocksDescendants"，表示 ViewGroup会覆盖子类控件而直接获取焦点；
    -->

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="200dp"
        android:layout_height="100dp">
        <TextView
            android:id="@+id/tvH2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="我是标题"
            android:gravity="center"
            android:textSize="16sp"
            android:textStyle="bold"
            />
        <ScrollView
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/tvCont2"
                android:layout_marginTop="10px"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="我是内容文本asdfasdfasdfasdfasdfasdfs"
                android:textSize="12sp"
                android:textStyle=""
                />
        </ScrollView>
    </LinearLayout>

    <ImageView
        android:id="@+id/btnImg2"
        android:layout_width="200dp"
        android:layout_height="100dp"
        android:scaleType="fitXY"
        android:src="@mipmap/bg"
        />
</LinearLayout>