Android : ListView + BaseAdapter-2简单应用-编程知识

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@Overridepublic int getCount() {//充的数据集数return date.size();}@Overridepublic Object getItem(int position) {//数据集中指定索引对应的数据项return date.get(position);}@Overridepublic long getItemId(int position) {// 指定行所对应的IDreturn position;}//重写 getItemViewType 返回对应的item布局类型@Overridepublic 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@Overridepublic int getViewTypeCount() {return 2;}//优化@Overridepublic 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;@Overrideprotected 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() {@Overridepublic 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"><ListViewandroid: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；--><ImageViewandroid:id="@+id/btnImg"android:layout_width="200dp"android:layout_height="100dp"android:scaleType="fitXY"android:src="@mipmap/bg"/><LinearLayoutandroid:orientation="vertical"android:layout_width="match_parent"android:layout_height="wrap_content"><TextViewandroid: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"/><ScrollViewandroid:layout_width="match_parent"android:layout_height="wrap_content"><TextViewandroid: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；--><LinearLayoutandroid:orientation="vertical"android:layout_width="200dp"android:layout_height="100dp"><TextViewandroid: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"/><ScrollViewandroid:layout_width="match_parent"android:layout_height="wrap_content"><TextViewandroid: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><ImageViewandroid:id="@+id/btnImg2"android:layout_width="200dp"android:layout_height="100dp"android:scaleType="fitXY"android:src="@mipmap/bg"/>
</LinearLayout>