ListView 是android开发中最常用的组件之一,它通过一个adapter来构建显示通常有三种adapter可以使用ArrayAdapter ,SimpleAdapter ,CursorAdapter。CursorAdapter主要正对数据库使用,下面通过例子介绍ArrayAdapter ,SimpleAdapter 的简单使用:
1:ArrayAdapter 它接受一个数组或者List作为参数来构建。
一下通过简单例子说明:
创建Test 继承ListActivity 这里我们传入一个string数组
public class ListTest extends ListActivity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
String[] sw = new String[ 100 ];
for ( int i = 0 ; i < 100 ; i ++ ) {
sw[i] = " listtest_ " + i;
}
ArrayAdapter < String > adapter = new ArrayAdapter < String > ( this ,android.R.layout.simple_list_item_1,sw);//使用系统已经实现好的xml文件simple_list_item_1
setListAdapter(adapter);
}
}
运行如图:
从以上代码可以看不我们不需要加载我们自己的layout 而是用系统已经实现的layout很快速的实现了listview
第二种SimpleAdapter :
先看下我们例子的最终截图:
通过上图可以看出listview每行不仅仅是一个string 包括了很多项,图片,多项文字
我们通过构建list,并设置每项为一个map来实现:
代码:创建TestList类继承Activity
super
.onCreate(savedInstanceState);
setContentView(R.layout.main);
ArrayList < HashMap < String, Object >> users = new ArrayList < HashMap < String, Object >>
();
for ( int i = 0 ; i < 10 ; i ++ )
{
HashMap < String, Object > user = new HashMap < String, Object > ();
user.put( " img " , R.drawable.user);
user.put( " username " , " 姓名( " + i + " ) " );
user.put( " age " , ( 20 + i) + "" );
users.add(user);
}
SimpleAdapter saImageItems
= new SimpleAdapter( this
,
users, // 数据来源
R.layout.user, // 每一个user xml 相当ListView的一个组件
new String[] { " img " , " username " , " age " }
,
// 分别对应view 的id
new int [] { R.id.img, R.id.name, R.id.age }
);
// 获取listview
((ListView) findViewById(R.id.users)).setAdapter(saImageItems);
下面是main.xml的内容:
<? xml version = " 1.0 " encoding = " utf-8 " ?>
< LinearLayout xmlns:android = " http://schemas.android.com/apk/res/android "
android:orientation
= " vertical " android:layout_width = " fill_parent "
android:layout_height
= " fill_parent " >
< TextView android:text = " 用户列表 " android:gravity = " center "
android:layout_height
= " wrap_content "
android:layout_width
= " fill_parent " android:background = " #DAA520 "
android:textColor
= " #000000 " >
</ TextView >
<
LinearLayout
android:layout_width = " wrap_content "
android:layout_height
= " wrap_content " >
< TextView android:text = " 姓名 "
android:gravity = " center " android:layout_width = " 160px "
android:layout_height
= " wrap_content " android:textStyle = " bold "
android:background
= " #7CFC00 " >
</ TextView >
< TextView android:text = " 年龄 "
android:layout_width = " 170px " android:gravity = " center "
android:layout_height
= " wrap_content " android:textStyle = " bold "
android:background
= " #F0E68C " >
</ TextView >
</ LinearLayout >
< ListView android:layout_width = " wrap_content "
android:layout_height = " wrap_content " android:id = " @+id/users " >
</ ListView >
</ LinearLayout >
之中listView前面的可以说是标题行,listview相当于用来显示数据的容器,里面每行是一个用户信息,而用户信息是样子呢?
看看use.xml
<? xml version = " 1.0 " encoding = " utf-8 " ?>
<
TableLayout
android:layout_width = " fill_parent "
xmlns:android = " http://schemas.android.com/apk/res/android "
android:layout_height = " wrap_content "
>
< TableRow >
<
ImageView
android:layout_width = " wrap_content "
android:layout_height = " wrap_content "
android:id = " @+id/img " >
</ ImageView >
<
TextView
android:layout_height = " wrap_content "
android:layout_width = " 150px "
android:id = " @+id/name " >
</ TextView >
<
TextView
android:layout_height = " wrap_content "
android:layout_width = " 170px "
android:id = " @+id/age " >
</ TextView >
</ TableRow >
</ TableLayout >
也就是说每行包含了一个img 和2个文字信息
这个文件以参数的形式通过adapter在listview中显示。
也就是:
SimpleAdapter saImageItems = new SimpleAdapter( this ,
users, // 数据来源
R.layout.user, // 每一个user xml 相当ListView的一个组件
new String[] { " img " , " username " , " age " } ,
// 分别对应view 的id
new int [] { R.id.img, R.id.name, R.id.age } );