同事！我有一个例外，我不知道如何避免。我在 SherlockFragmentActivity 中使用 ViewPager 创建了 TabHost。TabHost 包含片段。
活动：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tabs_fragment_layout);
mTabHost = (TabHost) findViewById(android.R.id.tabhost);
mViewPager = (ViewPager) findViewById(R.id.pager);
mTabHost.setup();
setupTabs();
if (savedInstanceState != null) {
mTabHost.setCurrentTabByTag(savedInstanceState.getString(CURRENT_TAB_KEY));
}
}
private void setupTabs() {
nameTabs = getResources().getStringArray(R.array.tabs);
mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager);
mTabsAdapter.addTab(newTab(TABS_TAG_1, R.drawable.ic_action_countries,
nameTabs[COUNTRIES_TAB_INDEX]), CountryTabFragment.class, null);
mTabsAdapter.addTab(newTab(TABS_TAG_2, R.drawable.ic_action_settings_dark,
nameTabs[SETTINGS_TAB_INDEX]),UltiPreferenceFragment.class, null);
mTabsAdapter.addTab(newTab(TABS_TAG_3, R.drawable.ic_action_about,
nameTabs[ABOUT_TAB_INDEX]), AboutFragment.class, null);
}
private TabSpec newTab (String tag, int iconId, String tabTitle) {
TabSpec tab = mTabHost.newTabSpec(tag);
tab.setIndicator(tabTitle, getResources().getDrawable(iconId));
return tab;
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(CURRENT_TAB_KEY, mTabHost.getCurrentTabTag());
}
private Fragment getFragmentByIndex(ViewPager container, int position) {
String name = makeFragmentName(container.getId(), position);
return getSupportFragmentManager().findFragmentByTag(name);
}
private String makeFragmentName(int viewId, int index) {
return getString(R.string.fragment_name_pattern, viewId, index);
}
public static class TabsAdapter extends FragmentPagerAdapter
implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final TabHost mTabHost;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
static final class TabInfo {
private final String tag;
private final Class<?> clss;
private final Bundle args;
TabInfo(String tag, Class<?> clss, Bundle args) {
this.tag = tag;
this.clss = clss;
this.args = args;
}
}
static class DummyTabFactory implements TabHost.TabContentFactory {
private final Context mContext;
public DummyTabFactory(Context context) {
mContext = context;
}
@Override
public View createTabContent(String tag) {
View view = new View(mContext);
view.setMinimumWidth(0);
view.setMinimumHeight(0);
return view;
}
}
public TabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mTabHost = tabHost;
mViewPager = pager;
mTabHost.setOnTabChangedListener(this);
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
mViewPager.setId(R.id.view_pager);
}
public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
tabSpec.setContent(new DummyTabFactory(mContext));
String tag = tabSpec.getTag();
TabInfo info = new TabInfo(tag, clss, args);
mTabs.add(info);
mTabHost.addTab(tabSpec);
notifyDataSetChanged();
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
@Override
public int getItemPosition(Object object) {
return PagerAdapter.POSITION_NONE;
}
@Override
public void onTabChanged(String tabId) {
int position = mTabHost.getCurrentTab();
mViewPager.setCurrentItem(position);
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
TabWidget widget = mTabHost.getTabWidget();
int oldFocusability = widget.getDescendantFocusability();
widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
mTabHost.setCurrentTab(position);
widget.setDescendantFocusability(oldFocusability);
}
@Override
public void onPageScrollStateChanged(int state) {
}
}
在 7 英寸设备上，我有 2 种布局用于 TabHost 的 FirstFragment，一种用于纵向和横向。当我旋转屏幕时，它必须更改布局。不幸的是，我无法重新创建活动，因为在这种情况下，我会丢失对话（DialogFragment）和其他长期进程的上下文，这些进程在旋转屏幕时在应用程序中可用。所以，1）我在 AndroidManifest.xml 中使用
android:configChanges="orientation|screenSize"
2）覆盖Activity中的onConfigurationChanged（）方法：
@Override
public void onConfigurationChanged(Configuration newConfig) {
int oldConfigOrientation = getRequestedOrientation();
super.onConfigurationChanged(newConfig);
if (newConfig.orientation != oldConfigOrientation) {
Toast.makeText(this, "orientation changed!", Toast.LENGTH_SHORT).show();
mTabsAdapter.notifyDataSetChanged();
}
}
3) 和 FragmentPagerAdapter 中的 ovveride getItemPosition()-方法用于选项卡的重新布局。当我旋转屏幕时出现问题，它应该加载一个片段而不是两个面板布局的单面板布局：
04-12 12:30:44.019: E/AndroidRuntime(11151): java.lang.IllegalArgumentException: No view found for id 0x7f05004f (com.ziko.widget:id/setup_layout_fragment) for fragment SetupCityFragment{410fac80 #1 id=0x7f05004f}
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:903)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1088)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1070)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1861)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1474)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:931)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.attachFragment(FragmentManager.java:1264)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:672)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1444)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:461)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.ViewPager.populate(ViewPager.java:1011)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:522)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:494)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:874)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:2688)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:35)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:276)
04-12 12:30:44.019: E/AndroidRuntime(11151): at com.ziko.widget.ui.ConfigurationActivity.onConfigurationChanged(ConfigurationActivity.java:140)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.app.ActivityThread.performConfigurationChanged(ActivityThread.java:3461)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.app.ActivityThread.handleConfigurationChanged(ActivityThread.java:3585)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1220)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.os.Handler.dispatchMessage(Handler.java:99)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.os.Looper.loop(Looper.java:137)
04-12 12:30:44.019: E/AndroidRuntime(11151): at android.app.ActivityThread.main(ActivityThread.java:4424)
04-12 12:30:44.019: E/AndroidRuntime(11151): at java.lang.reflect.Method.invokeNative(Native Method)
04-12 12:30:44.019: E/AndroidRuntime(11151): at java.lang.reflect.Method.invoke(Method.java:511)
04-12 12:30:44.019: E/AndroidRuntime(11151): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
04-12 12:30:44.019: E/AndroidRuntime(11151): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
04-12 12:30:44.019: E/AndroidRuntime(11151): at dalvik.system.NativeStart.main(Native Method)
当我将屏幕从单面板（纵向）布局旋转到两面板（横向）时，从来没有发生过这个问题，但总是相反。调用方法 mTabsAdapter.notifyDataSetChanged() 时抛出异常；在 onConfigurationChanged() 中。
谁能解释异常的原因以及将来如何避免它？也许还有另一种方式如何在旋转屏幕时提供更改选项卡的布局？