ArrayAdapter
数组适配器，仅能显示一行文本数据
<?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="vertical">
<ListView
android:id="@+id/lv_list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MainActivity extends Activity {
// 定义要显示的数据
private String[] datas = {"张三", "李四", "王五", "麻子", "小强"};
private ArrayAdapter<String> adapter;
private ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.lv_list);
// 初始化适配器
adapter = new ArrayAdapter<>(this, android.R.layout.simple_expandable_list_item_1, datas);
listView.setAdapter(adapter);
}
}
可以在value创建数组资源xml文件arrays.xml，在listview中使用entries
<resources>
<string-array name = "list">
<item>张三</item>
<item>李四</item>
<item>王五</item>
<item>麻子</item>
<item>小强</item>
</string-array>
</resources>
<ListView
android:id="@+id/lv_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:entries="@array/list">
</ListView>
datas = getResources().getStringArray(R.array.list);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String result = parent.getItemAtPosition(position).toString();
Toast.makeText(MainActivity.this, result, Toast.LENGTH_SHORT).show();
}
});
ArrayAdapter参数说明
- 第一个参数，context上下文对象
- 第二个参数，item样式，可以使用系统提供，可以自定义TextView
- 第三个参数，数据源
系统提供item样式
- simple_list_item1，单行文本框（text）
- simple_list_item2，两行文本框（title与text）
- simple_list_item_checked，复选框（已选中）
- simple_list_item_multiple_choice，复选框
- simple_list_item_single_choice，单选框
SimpleAdapter
简单适配器
<?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="vertical">
<ListView
android:id="@+id/lv_list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView
android:id="@+id/iv_image"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@mipmap/ic_launcher"
android:layout_margin="5dp"/>
<LinearLayout
android:id="@+id/ll_info"
android:layout_width="match_parent"
android:layout_height="100dp"
android:orientation="vertical"
android:layout_marginTop="5dp"
android:layout_marginLeft="10dp">
<TextView
android:id="@+id/tv_theme"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="30sp"
android:layout_marginTop="10dp"/>
<TextView
android:id="@+id/tv_content"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="24dp"
android:layout_marginTop="10dp"/>
</LinearLayout>
</LinearLayout>
import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MainActivity extends Activity {
private List<Map<String,Object>> lists;
private SimpleAdapter adapter;
private ListView listView;
// 定义数据
private String[] theme = {"张三", "李四", "王五"};
private String[] content = {"我是张三，你好", "我是李四，你好", "我是王五，你好"};
private int[] imageViews = {R.mipmap.ic_launcher, R.mipmap.ic_account, R.mipmap.ic_password};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.lv_list);
// 准备数据源
lists = new ArrayList<>();
for(int i = 0; i < theme.length; i++) {
Map<String,Object> map = new HashMap<>();
map.put("image", imageViews[i]);
map.put("theme", theme[i]);
map.put("content", content[i]);
lists.add(map);
}
adapter = new SimpleAdapter(MainActivity.this, lists, R.layout.list_item, new String[]{"image", "theme", "content"}, new int[]{R.id.iv_image, R.id.tv_theme, R.id.tv_content});
listView.setAdapter(adapter);
}
}
SimpleAdapter参数说明
- 第一个参数，上下文对象
- 第二个参数，数据源（集合，元素类型Map）
- 第三个参数，item布局文件
- 第四个参数，String数组，数组元素与数据源Map的key一一对应
- 第五个参数，int数组，item布局文件的控件id
BaseAdapter
import android.content.Context;
import android.text.Layout;
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.ArrayList;
import java.util.List;
public class InfoAdapter extends BaseAdapter {
private List<Message> datas;
private Context mContext;
public MyAdapter(List<Message> datas, Context mContext) {
Datas = datas;
this.mContext = mContext;
}
/**
* 返回item个数
* @return
*/
@Override
public int getCount() {
return datas.size();
}
/**
* 返回单个item对象
* @param i
* @return
*/
@Override
public Object getItem(int i) {
return datas.get(i);
}
/**
* 返回单个item的id
* @param i
* @return
*/
@Override
public long getItemId(int i) {
return i;
}
/**
* 暂不进行优化处理
* @param i
* @param view
* @param viewGroup
* @return
*/
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
view = LayoutInflater.from(mContext).inflate(R.layout.list_item, viewGroup, false);
ImageView iv_image = (ImageView) view.findViewById(R.id.iv_image);
TextView tv_theme = (TextView) view.findViewById(R.id.tv_theme);
TextView tv_content = (TextView) view.findViewById(R.id.tv_content);
iv_image.setImageResource(Datas.get(i).getImageId());
tv_theme.setText(Datas.get(i).getTheme());
tv_content.setText(Datas.get(i).getContent());
return view;
}
}
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 {
private List<Message> lists;
private InfoAdapter adapter;
private ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.ll_list);
lists = new ArrayList<>();
lists.add(new Message(R.mipmap.ic_launcher, "张三", "你好，我是张三"));
lists.add(new Message(R.mipmap.ic_account, "李四", "你好，我是李四"));
lists.add(new Message(R.mipmap.ic_password, "王五", "你好，我是王五"));
adapter = new InfoAdapter(lists, MainActivity.this);
listView.setAdapter(adapter);
}
}
利用Listview缓存机制但findviewbyid反复使用
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// 若view未被实例化，缓存池无对应缓存
if (convertView == null) {
convertView = mInflater.inflate(R.layout.item, null);
}
/**
* 获取item布局文件对应控件
*/
ImageView imageView = (ImageView) convertView.findViewById(R.id.iv_image);
TextView titleTextView = (TextView) convertView.findViewById(R.id.tv_theme);
TextView contentTextView = (TextView) convertView.findViewById(R.id.tv_content);
// 获取相应索引ItemBean对象
ItemBean bean = mList.get(position);
/**
* 设置控件的对应属性值
*/
imageView.setImageResource(bean.itemImageResId);
titleTextView.setText(bean.itemTheme);
contentTextView.setText(bean.itemContent);
return convertView;
}
- 创建bean对象，用于封装数据
- 在构造方法中初始化数据List
- 创建ViewHolder类，创建布局映射关系
- 判断convertView，为空则创建并设置tag，不为空则通过tag取出ViewHolder
- 给ViewHolder控件设置数据
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
// 若view未被实例化过，缓存池无对应缓存
if (convertView == null) {
viewHolder = new ViewHolder();
// 仅需将XML转化为View，不涉及布局，第二个参数设置为null
convertView = mInflater.inflate(R.layout.item, null);
// 对viewHolder属性进行赋值
viewHolder.imageView = (ImageView) convertView.findViewById(R.id.iv_image);
viewHolder.theme = (TextView) convertView.findViewById(R.id.tv_theme);
viewHolder.content = (TextView) convertView.findViewById(R.id.tv_content);
// 通过setTag将convertView与viewHolder关联
convertView.setTag(viewHolder);
} else {
// 若缓存池有对应view缓存，则通过getTag取出viewHolder
viewHolder = (ViewHolder) convertView.getTag();
}
// 取出bean对象
ItemBean bean = mList.get(position);
// 设置控件的数据
viewHolder.imageView.setImageResource(bean.itemImageResId);
viewHolder.title.setText(bean.itemTheme);
viewHolder.content.setText(bean.itemContent);
return convertView;
}
// ViewHolder用于缓存控件，属性对应item布局文件控件
class ViewHolder{
public ImageView imageView;
public TextView theme;
public TextView content;
}
