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我讀過關於使用相對佈局的ListView優化佈局此博客條目： http://android-developers.blogspot.com/2009/02/android-layout-tricks-1.html需要幫助使用Android的佈局技巧＃1
我已經使用這個佈局我的ListView項（具備稍作修改例如）：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="?android:attr/listPreferredItemHeight"
android:padding="6dip">
<ImageView
android:id="@+id/icon"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_marginRight="6dip"
android:src="@drawable/icon" />
<TextView
android:id="@+id/secondLine"
android:layout_width="fill_parent"
android:layout_height="26dip"
android:layout_toRightOf="@id/icon"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:singleLine="true"
android:ellipsize="marquee"/>
<TextView
android:id="@+id/text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/icon"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_above="@id/secondLine"
android:layout_alignWithParentIfMissing="true"
android:gravity="center_vertical" />
</RelativeLayout>
而且我修改了APIDemo中的List14.java以使用該ListItem視圖。但是當我在仿真器上運行它時，我只看到圖標，文本是空白的。而當我打開HierarchyViewer文本視圖的高度爲0.有人可以告訴我爲什麼？
public class TestListView extends ListActivity {
private static class EfficientAdapter extends BaseAdapter {
private LayoutInflater mInflater;
private Bitmap mIcon1;
private Bitmap mIcon2;
public EfficientAdapter(Context context) {
// Cache the LayoutInflate to avoid asking for a new one each time.
mInflater = LayoutInflater.from(context);
// Icons bound to the rows.
mIcon1 = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon48x48_1);
mIcon2 = BitmapFactory.decodeResource(context.getResources(), R.drawable.icon48x48_2);
}
/**
* The number of items in the list is determined by the number of speeches
* in our array.
*
* @see android.widget.ListAdapter#getCount()
*/
public int getCount() {
return DATA.length;
}
/**
* Since the data comes from an array, just returning the index is
* sufficent to get at the data. If we were using a more complex data
* structure, we would return whatever object represents one row in the
* list.
*
* @see android.widget.ListAdapter#getItem(int)
*/
public Object getItem(int position) {
return position;
}
/**
* Use the array index as a unique id.
*
* @see android.widget.ListAdapter#getItemId(int)
*/
public long getItemId(int position) {
return position;
}
/**
* Make a view to hold each row.
*
* @see android.widget.ListAdapter#getView(int, android.view.View,
* android.view.ViewGroup)
*/
public View getView(int position, View convertView, ViewGroup parent) {
// A ViewHolder keeps references to children views to avoid unneccessary calls
// to findViewById() on each row.
ViewHolder holder;
// When convertView is not null, we can reuse it directly, there is no need
// to reinflate it. We only inflate a new View when the convertView supplied
// by ListView is null.
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_item_icon_text, null);
// Creates a ViewHolder and store references to the two children views
// we want to bind data to.
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(R.id.text);
holder.icon = (ImageView) convertView.findViewById(R.id.icon);
convertView.setTag(holder);
} else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
// Bind the data efficiently with the holder.
holder.text.setText(DATA[position]);
holder.icon.setImageBitmap((position & 1) == 1 ? mIcon1 : mIcon2);
return convertView;
}
static class ViewHolder {
TextView text;
ImageView icon;
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setListAdapter(new EfficientAdapter(this));
}
private static final String[] DATA = {
"Abbaye de Belloc", "Abbaye du Mont des Cats", "Abertam",
"Zanetti Grana Padano", "Zanetti Parmigiano Reggiano"};
}
}
謝謝。我從來沒有想過這樣做。 – hap497 2010-02-09 18:21:45
在上面的例子中，它表示「android：layout_alignParentRight =」true「，但是爲什麼當我在模擬器上運行時，TextView是與父對象左對齊的？ – hap497 2010-02-09 19:21:46
不知道我是否正確理解了你。 這裏是我的想法：alignParentRight這裏的意思是「將TextView的右邊框與父元素的右邊框對齊」，即LinearLayout。當然，這基本上意味着將TextView放置在LinearLayout的右邊界的左側。 TextView的文本內容與左側對齊，因爲如果不在TextView上設置android：gravity，那麼這是默認值。 這有幫助嗎？ – rflexor 2010-02-10 12:21:45