我的目标是平板电脑3.2版。我在屏幕左侧显示listactivity，当用户点击listitem时，屏幕右侧会显示详细信息。因为我点击了每个项目的不同细节布局我在屏幕右侧显示一个片段。我需要在详细信息部分的选项卡式布局上显示。我扩展了一个片段，在oncreateview中用tabhost作为根元素膨胀了一个xml。但不知何故，片段没有膨胀。对于每个选项卡，我有一个列表视图要显示。下面是代码部分...我得到的错误是NullPointerException。
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
public class Projects extends Fragment implements OnTabChangeListener {
private int mCurrentTab;
private TabHost mTabHost;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View tablayout = inflater.inflate(R.layout.projects, null);
mTabHost = (TabHost)tablayout.findViewById(android.R.id.tabhost);
final View v1 = tablayout.findViewById(R.id.webprojects);
final View v2 = tablayout.findViewById(R.id.androidprojects);
final View v3 = tablayout.findViewById(R.id.iphoneprojects);
mTabHost.addTab(mTabHost.newTabSpec("tab1").setIndicator("WEB").setContent(new TabHost.TabContentFactory() {
public View createTabContent(String tag) {
// TODO Auto-generated method stub
return v1;
}
}));
mTabHost.addTab(mTabHost.newTabSpec("tab2").setIndicator("ANDROID").setContent(new TabHost.TabContentFactory() {
@Override
public View createTabContent(String tag) {
// TODO Auto-generated method stub
return v2;
}
}));
mTabHost.addTab(mTabHost.newTabSpec("tab3").setIndicator("IPHONE").setContent(new TabHost.TabContentFactory() {
@Override
public View createTabContent(String tag) {
// TODO Auto-generated method stub
return v3;
}
}));
return tablayout;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
setRetainInstance(true);
mTabHost.setOnTabChangedListener(this);
mTabHost.setCurrentTab(mCurrentTab);
}
@Override
public void onTabChanged(String tabId) {
// TODO Auto-generated method stub
FragmentTransaction FrgTra = getFragmentManager().beginTransaction();
if(tabId.equals("WEB"))
{
if(getFragmentManager().findFragmentByTag(tabId) == null)
{
FrgTra.replace(R.id.webprojects, new ProjectsListFragment("WEB"), tabId).commit();
}
}
if(tabId.equals("ANDROID"))
{
if(getFragmentManager().findFragmentByTag(tabId) == null)
{
FrgTra.replace(R.id.androidprojects, new ProjectsListFragment("ANDROID"), tabId).commit();
}
}
if(tabId.equals("IPHONE"))
{
if(getFragmentManager().findFragmentByTag(tabId) == null)
{
FrgTra.replace(R.id.iphoneprojects, new ProjectsListFragment("IPHONE"), tabId).commit();
}
}
}
}
我正在使用的xml是：
<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TabWidget android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0" />
<FrameLayout android:id="@android:id/tabcontent"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="0">
<FrameLayout android:id="@+id/webprojects"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
</FrameLayout>
<FrameLayout
android:id="@+id/androidprojects"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
</FrameLayout>
<FrameLayout
android:id="@+id/iphoneprojects"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
</FrameLayout>
</FrameLayout>
</LinearLayout>
</TabHost>
请帮我解决这个问题......
答案 0 :(得分：0)
不确定您的内容是否已正确初始化 新的TabHost.TabContentFactory（） 调用
我发现填充Tab需要一个可能需要额外信息来提取信息的活动，例如游标ID。然后，您可能需要设置选项卡上显示的文本以及图标或图标选择器，以便选项卡选择更适合您的用户体验。
Resources _res = app.getResources();
// Create an Intent to launch an Activity for the tab (to be reused)
Intent _intent = new Intent().setClass(this, WEB_TabActivity.class);
_intent.putExtra("whenNeeded", whenNeeded);
// Initialize a TabSpec for each tab and add it to the TabHost
tabHost.addTab(tabHost.newTabSpec("WEB")
.setIndicator(_res.getString(R.string.WEB_Displayed_Tab_Text),
_res.getDrawable(R.drawable.WEB_icon_selector))
.setContent(_intent));
示例选择器是：
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<!-- When selected, use color-->
<item android:drawable="@drawable/WEB_ICON_color"
android:state_selected="true" />
<!-- When not selected, use grey -->
<item android:drawable="@drawable/WEB_ICON_Grey" />
</selector>
然后将WEB_TabActivity编码为任何可显示所需数据的Activity类。
答案 1 :(得分：0)
** CURSOR ADAPTER和VIEW HOLDER PATTERN
/**
* Adapter that allows us to match product items to layout fragment<p/>
*
* @author The Solar Sheriff
*/
public class MyItemListAdapter extends CursorAdapter {
public final static String TAG = "MyItemListAdapter";
/**
* Constructor from a list of items
*/
private LayoutInflater _li;
private Context _context;
private Cursor _in;
private int _productName,
_count;
public OrderItemListAdapter(Context _Context, Cursor _In) {
super(_Context, _In, true);
_context = _Context;
_li = LayoutInflater.from(_context);
_in = _In;
_productName = _in.getColumnIndex("product_name");
_count = _in.getCount();
}
@Override
public Object getItem(int position) {
return position;
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public int getCount() {
return _in.getCount();
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
View _view = _li.inflate(R.layout.list_item_layout, null);
return _view;
}
private ViewHolder mapItemViewHolder(View _v){
ViewHolder _itemHolder = new ViewHolder();
//Map the views to the ViewHolder
_itemHolder.productName = (TextView) _v.findViewById(R.id.itemProductName);
return _itemHolder;
}
@Override
public void bindView(View _cView, final Context _context, final Cursor _c) {
ViewHolder _itemHolder;
// 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 (_cView == null) {
_cView = _li.inflate(R.layout.list_item_layout, null);
_itemHolder = mapItemViewHolder(_cView);
_cView.setTag(_itemHolder);
}
else {
// Get the ViewHolder back to get fast access
// Can also get a view with no tag so check for null
if ((_itemHolder = (ViewHolder) _cView.getTag()) == null) {
_itemHolder = mapItemViewHolder(_cView);
_cView.setTag(_itemHolder);
}
}
//*** TEXT VIEWS ***
// Bind the data using the holder.
_itemHolder.productName.setText(_c.getString(_productName));
for(String _display : TabLayouts ) {
if ( _display.equals("WEB") ) _itemHolder.productName.setTag(Integer.toString(R.layout.WEB_layout));
if ( _display.equals("IPHONE") ) _itemHolder.productName.setTag(Integer.toString(R.layout.IPHONE_layout));
if ( _display.equals("ANDROID") ) _itemHolder.productName.setTag(Integer.toString(R.layout.ANDROID_layout));
}
}
static String TabLayouts = { "WEB","IPHONE","ANDROID"};
static class ViewHolder
{
TextView productName;
}
}
//你的onSelectedItem LISTENER
MyList.setOnItemSelectedListener( new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> _item, View _View, int _selection, long _id) {
ViewGroup _parent = (ViewGroup)_item.getParent();
TextView _productName = (TextView)_parent.findViewById(R.id.itemProductName);
int _showLayout = Integer.valueOf(_productName.getTag());
//*** e.g. Inflate your fragment layout ***
}
});
希望这能为您提供一条成功的道路：）