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Android: ListView与Button的共存问题解决
ListView 和 其它能触发点击事件的widget无法一起正常工作的原因是加入其它widget后,ListView的itemclick事件将无法触发,被其它widget的click事件屏蔽。
- 首先,说明一下,ListView中每一行包括以下三项:
一个ImageView, 一个TextView,一个ImageButton,依次排开。
以下是layout的内容,分为两部分:
- res/layout/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:padding="10dip" android:orientation="vertical"> <ListView android:id="@id/android:list" android:layout_width="fill_parent" android:layout_height="fill_parent" /></LinearLayout>
res/layout/lvitem.xml因为继承了ListActivity,所以ListView 的id设置为"@id/android:list"是必须的
注意:
在<RelativeLayout>中
android:descendantFocusability="blocksDescendants"
和<ImageButton>中
android:focusable="false"
这两项的设置很关键,如果不设置,将导致ListView的ItemClick事件将无法触发,该事件被ImageButton的click事件屏蔽了。
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:padding="5dip" android:descendantFocusability="blocksDescendants" > <ImageView android:id="@+id/ItemImage" android:layout_width="wrap_content" android:layout_height="wrap_content" android:padding="5dip" /> <!-- 把按钮背景设置为透明: android:background="#00000000" 把按钮背景设置为半透明: android:background="#e0000000" --> <ImageButton android:id="@+id/ItemCloseWin" android:layout_alignParentRight="true" android:layout_alignTop="@+id/ItemWinName" android:layout_alignBottom="@+id/ItemWinName" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="#e0000000" android:gravity="left|center_vertical" android:focusable="false" android:src="@android:drawable/ic_menu_close_clear_cancel" /> <TextView android:id="@+id/ItemWinName" android:layout_toRightOf="@+id/ItemImage" android:layout_toLeftOf="@+id/ItemCloseWin" android:layout_alignTop="@+id/ItemImage" android:layout_alignBottom="@+id/ItemImage" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="left|center_vertical" android:textSize="20dip" android:text="title" /> </RelativeLayout>
在lvWithButtonExt中,为了能处理ImageButton的click事件,我继承了BaseAdapter类,并重新实现了getView()接口,在其中加入了Button的clicklistener,详见lvButtonAdapter类的实现。接下来,我们看看继承ListActivity的实现
public class lvWithButtonExt extends ListActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // 关联Layout中的ListView ListView vncListView = (ListView)findViewById(android.R.id.list); // 生成动态数组,加入数据 ArrayList<HashMap<String, Object>> remoteWindowItem = newArrayList<HashMap<String, Object>>(); for(int i=0;i<10;i++) { HashMap<String, Object> map = new HashMap<String, Object>(); map.put("ItemImage", R.drawable.firefox);//图像资源的ID map.put("ItemWinName", "Window ID "+i); map.put("ItemCloseWin",android.R.drawable.ic_menu_close_clear_cancel); remoteWindowItem.add(map); } // 生成适配器的Item和动态数组对应的元素 lvButtonAdapter listItemAdapter = new lvButtonAdapter( this, remoteWindowItem,//数据源 R.layout.lvitem,//ListItem的XML实现 //动态数组与ImageItem对应的子项 new String[] {"ItemImage","ItemWinName", "ItemCloseWin"}, //ImageItem的XML文件里面的一个ImageView,两个TextView ID new int[] {R.id.ItemImage,R.id.ItemWinName,R.id.ItemCloseWin} ); vncListView.setAdapter(listItemAdapter); } @Override protected void onListItemClick(ListView l, View v, int position, long id){ // TODO Auto-generated method stub super.onListItemClick(l, v, position, id); l.getItemAtPosition(position); }}
为了响应按钮的点击事件,首先要记录按钮的位置,然后为按钮设置clicklistener。接下来,我们看看lvButtonAdapter的实现
在重新实现的getView()接口中,我使用了lvButtonListener监听类,在构造函数中,记录行号,以便在OnClick接口中能准确的定位按钮所在的位置,进而对相应的行进行处理。
public class lvButtonAdapter extends BaseAdapter { private class buttonViewHolder { ImageView appIcon; TextView appName; ImageButton buttonClose; } private ArrayList<HashMap<String, Object>> mAppList; private LayoutInflater mInflater; private Context mContext; private String[] keyString; private int[] valueViewID; private buttonViewHolder holder; public lvButtonAdapter(Context c, ArrayList<HashMap<String, Object>> appList, int resource, String[] from, int[] to) { mAppList = appList; mContext = c; mInflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); keyString = new String[from.length]; valueViewID = new int[to.length]; System.arraycopy(from, 0, keyString, 0, from.length); System.arraycopy(to, 0, valueViewID, 0, to.length); } @Override public int getCount() { return mAppList.size(); } @Override public Object getItem(int position) { return mAppList.get(position); } @Override public long getItemId(int position) { return position; } public void removeItem(int position){ mAppList.remove(position); this.notifyDataSetChanged(); } @Override public View getView(int position, View convertView, ViewGroup parent) { if (convertView != null) { holder = (buttonViewHolder) convertView.getTag(); } else { convertView = mInflater.inflate(R.layout.lvitem, null); holder = new buttonViewHolder(); holder.appIcon = (ImageView)convertView.findViewById(valueViewID[0]); holder.appName = (TextView)convertView.findViewById(valueViewID[1]); holder.buttonClose = (ImageButton)convertView.findViewById(valueViewID[2]); convertView.setTag(holder); } HashMap<String, Object> appInfo = mAppList.get(position); if (appInfo != null) { String aname = (String) appInfo.get(keyString[1]); int mid = (Integer)appInfo.get(keyString[0]); int bid = (Integer)appInfo.get(keyString[2]); holder.appName.setText(aname); holder.appIcon.setImageDrawable(holder.appIcon.getResources().getDrawable(mid)); holder.buttonClose.setImageDrawable(holder.buttonClose.getResources().getDrawable(bid)); holder.buttonClose.setOnClickListener(new lvButtonListener(position)); } return convertView; } class lvButtonListener implements OnClickListener { private int position; lvButtonListener(int pos) { position = pos; } @Override public void onClick(View v) { int vid=v.getId(); if (vid == holder.buttonClose.getId()) removeItem(position); } }}
点击右边的按钮该行将被删除以下是运行效果图:
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