Android常用组件之ListView

使用ListAdapter是ListView的适配器。

使用ListView.setAdapter()方法来设置ListView的适配器。

1. 简单的使用

adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1); adapter.add("hello"); adapter.add("eoe"); lv.setAdapter(adapter);

R前面的android表示使用的是系统提供给我们的资源。

1. 使用自定义的资源

在layout包下新建一个XML，内容如下：

<?xml version="1.0" encoding="utf-8"?> <ListView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > </ListView>

然后如下所示，创建Adapter：

adapter = new ArrayAdapter<String>(this,R.layout.list_cell_view); adapter.add("hello"); adapter.add("eoe"); lv.setAdapter(adapter);

1. 自定义Adapter

private BaseAdapter adapter = new BaseAdapter() {         private String[] data = {"user1","user2","user3","user4","user5","user6",     "user7","user8","user9","user10","user11","user12","user13","user14",};     @Override     public View getView(int position, View convertView, ViewGroup parent) {         TextView tv = new TextView(MainActivity.this);         tv.setText(getItem(position));         return tv;     }              @Override     public long getItemId(int position) {         return position;     }              @Override     public String getItem(int position) {         return data[position];     }              @Override     public int getCount() {         return data.length;     } };

程序运行时，界面上显示多少个列表项，getView方法就是被执行多少次。

getView参数中的View表示被系统回收的View。

优化：

TextView tv = null; if (convertView!=null){     tv = (TextView) convertView; }else {     tv = new TextView(MainActivity.this); } tv.setText(getItem(position));

1. 创建一个可以显示图片的ListView

在layout中新建一个Linearlayout布局的文件：

<?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:layout_width="120dp" android:layout_height="120dp" android:id="@+id/icon"/> <LinearLayout android:layout_weight="1" android:layout_width="0dp" android:layout_height="match_parent" android:orientation="vertical"> <TextView android:id="@+id/name" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <TextView android:id="@+id/dec" android:layout_width="wrap_content" android:layout_height="wrap_content"/> </LinearLayout>   </LinearLayout>

创建一个Adapter：

private BaseAdapter adapter = new BaseAdapter() { private ListCellData[] data = new ListCellData[]{     new ListCellData("小明",     "男", android.R.drawable.ic_btn_speak_now),     new ListCellData("小丽",     "女", android.R.drawable.ic_dialog_dialer), };     @Override     public View getView(int position, View convertView, ViewGroup parent) {         LinearLayout line = null;         if (convertView!=null){             line = (LinearLayout) convertView;         }else {             line = (LinearLayout) LayoutInflater.from(MainActivity.this).inflate(R.layout.list_cell_view, null);         }         ListCellData item = getItem(position);         ImageView image = (ImageView) line.findViewById(R.id.icon);         TextView name = (TextView) line.findViewById(R.id.name);         TextView dec = (TextView) line.findViewById(R.id.dec);         image.setImageResource(item.getIcon());         name.setText(item.getUsername());         dec.setText(item.getSex());         return line;     }              @Override     public long getItemId(int position) {         return position;     }              @Override     public ListCellData getItem(int position) {         return data[position];     }          @Override     public int getCount() {         return data.length;     } };