Android BaseAdapter的使用

2019-11-09 15:22:23

字体：大中小

来源：转载

供稿：网友

现在有许多的适配器供我们使用，但是我们发现处理复杂的itmes使往往使用的是BaseAdapter，下面上代码

main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <ListView android:id="@+id/lv" android:layout_width="fill_parent" android:layout_height="wrap_content" android:fastScrollEnabled="true" /></LinearLayout>

list_item.xml

<?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="match_parent" android:orientation="horizontal" > <ImageView android:id="@+id/img" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="vertical" > <TextView android:id="@+id/tv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="20sp" /> <TextView android:id="@+id/info" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="14sp" /> </LinearLayout></LinearLayout>

Activity

package com.loulijun.demo17;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.ListView;import android.widget.TextView;public class Demo17Activity extends Activity { PRivate ListView lv; private List<Map<String, Object>> data; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); lv = (ListView)findViewById(R.id.lv); //获取将要绑定的数据设置到data中 data = getData(); MyAdapter adapter = new MyAdapter(this); lv.setAdapter(adapter); } private List<Map<String, Object>> getData() { List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); Map<String, Object> map; for(int i=0;i<10;i++) { map = new HashMap<String, Object>(); map.put("img", R.drawable.ic_launcher); map.put("title", "跆拳道"); map.put("info", "快乐源于生活..."); list.add(map); } return list; } //ViewHolder静态类 static class ViewHolder { public ImageView img; public TextView title; public TextView info; } public class MyAdapter extends BaseAdapter { private LayoutInflater mInflater = null; private MyAdapter(Context context) { //根据context上下文加载布局，这里的是Demo17Activity本身，即this this.mInflater = LayoutInflater.from(context); } @Override public int getCount() { //How many items are in the data set represented by this Adapter. //在此适配器中所代表的数据集中的条目数 return data.size(); } @Override public Object getItem(int position) { // Get the data item associated with the specified position in the data set. //获取数据集中与指定索引对应的数据项 return position; } @Override public long getItemId(int position) { //Get the row id associated with the specified position in the list. //获取在列表中与指定索引对应的行id return position; } //Get a View that displays the data at the specified position in the data set. //获取一个在数据集中指定索引的视图来显示数据 @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder = null; //如果缓存convertView为空，则需要创建View if(convertView == null) { holder = new ViewHolder(); //根据自定义的Item布局加载布局 convertView = mInflater.inflate(R.layout.list_item, null); holder.img = (ImageView)convertView.findViewById(R.id.img); holder.title = (TextView)convertView.findViewById(R.id.tv); holder.info = (TextView)convertView.findViewById(R.id.info); //将设置好的布局保存到缓存中，并将其设置在Tag里，以便后面方便取出Tag convertView.setTag(holder); }else { holder = (ViewHolder)convertView.getTag(); } holder.img.setBackgroundResource((Integer)data.get(position).get("img")); holder.title.setText((String)data.get(position).get("title")); holder.info.setText((String)data.get(position).get("info")); return convertView; } }}

运行结果如下：

输入图片说明