MainActivity
package com.example.administrator.baseadapter;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity {
@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,"我是标题"+i,"我是内容"+i));
}
ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(new MyAdapter(this,itemBeanList));
}
}class ItemBean
//此类用来封装对象
public class ItemBean {
public int ItemImage;
public String ItemTitlel;
public String ItemContent;
public ItemBean(int itemImage, String itemTitlel, String itemContent) {
ItemImage = itemImage;
ItemTitlel = itemTitlel;
ItemContent = itemContent;
}
}class Myadapter
public class MyAdapter extends BaseAdapter {
private LayoutInflater mInflater;
private List<ItemBean>mList;//创建一个成员变量用来保存传递进来的数据
public MyAdapter(Context context,List<ItemBean>list){ //数据源与适配器关联，为了从数据源中获取要传进来的数据，
// 通常在BaseAdapter的构造方法中对数据进行初始化
mList = list;
mInflater = LayoutInflater.from(context); //context 要使用当前的Adapter的界面对象mInflater布局装载对象，
// 传递进一个Context对象来初始化Inflater对象
}
@Override
public int getCount() {
return mList.size();
}
@Override
public Object getItem(int position) {
return mList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) { //返回每一项的显示内容
ViewHolder viewHolder;
if (convertView == null){
viewHolder = new ViewHolder();
convertView = mInflater.inflate(R.layout.item,null);
viewHolder.image= (ImageView) convertView.findViewById(R.id.image);
viewHolder.title = (TextView) convertView.findViewById(R.id.title);//通过viewHolder的对象将findViewById找到的对象保存起来
viewHolder.content = (TextView) convertView.findViewById(R.id.content);
convertView.setTag(viewHolder);//建立convertView与viewHolder的关联关系
}
else{
viewHolder = (ViewHolder) convertView.getTag();
}
ItemBean bean = mList.get(position);
viewHolder.image.setImageResource(bean.ItemImage);
viewHolder.title.setText(bean.ItemTitlel);
viewHolder.content.setText(bean.ItemContent);
return convertView;
/*不仅利用了ListView的缓存机制，更用过ViewHolder类来实现显示数据的视图缓存，
避免多次通过findViewById来寻找控件。
*/
}
class ViewHolder { //创建内部类ViewHolder
public ImageView image;
public TextView title; //避免重复的findViewById操作
public TextView content;
}
}
下面是布局文件
activity_main
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.administrator.baseadapter.MainActivity">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/listview"></ListView>
</RelativeLayout>
Item.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:layout_width="60dp"
android:layout_height="60dp"
android:id="@+id/image"
android:src="@mipmap/ic_launcher"/>
<TextView
android:layout_width="match_parent"
android:layout_height="30dp"
android:layout_toRightOf="@+id/image"
android:text="Title"
android:gravity="center"
android:textSize="20sp"
android:id="@+id/title"/>
<TextView
android:layout_width="match_parent"
android:layout_height="30dp"
android:layout_toRightOf="@+id/image"
android:layout_below="@+id/title"
android:text="Content"
android:textSize="20sp"
android:id="@+id/content"/>
</RelativeLayout>
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