【发布时间】：2015-09-03 22:45:51
【问题描述】：
我有一个TabHost 在一个navigationDrawer 里面，当我从作为导航抽屉项目存在的TabHost 转到另一个导航抽屉项目并返回@987654326 时，就会出现这个奇怪的问题@它不会显示它的内容，第一次它工作得很好但是当我改变项目并回到它时，它不会显示内容；换句话说，它不会加载子片段，除非我关闭应用程序并重新启动它或更改方向（重新创建片段）。
我第一次打开它时的样子（带有内容）
去另一个navDrawer Item后返回TabHost
TabHost 片段：
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TabHost;
import android.widget.TabWidget;
import java.util.ArrayList;
import info.fds.Emirates.R;
public class MyFragment extends Fragment
{
private TabHost mTabHost;
private ViewPager mViewPager;
private TabsAdapter mTabsAdapter;
public MyFragment() {
}
@Override
public void onCreate(Bundle instance)
{
super.onCreate(instance);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_main, container, false);
mTabHost = (TabHost) v.findViewById(android.R.id.tabhost);
mTabHost.setup();
mViewPager = (ViewPager) v.findViewById(R.id.pager);
mTabsAdapter = new TabsAdapter(getActivity(), mTabHost, mViewPager);
return v;
}
@Override
public void onResume() {
super.onResume();
// Here we load the content for each tab.
mTabsAdapter.addTab(mTabHost.newTabSpec("Incident").setIndicator("Incident"), PageOneFragment.class, null);
mTabsAdapter.addTab(mTabHost.newTabSpec("Service Request").setIndicator("Service Request"), PageTwoFragment.class, null);
}
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<?> _class, Bundle _args)
{
tag = _tag;
clss = _class;
args = _args;
}
}
static class DummyTabFactory implements TabHost.TabContentFactory
{
private final Context mContext;
public DummyTabFactory(Context context)
{
mContext = context;
}
public View createTabContent(String tag)
{
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
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);
}
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);
}
public void onTabChanged(String tabId)
{
int position = mTabHost.getCurrentTab();
mViewPager.setCurrentItem(position);
}
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
{
}
public void onPageSelected(int position)
{
// Unfortunately when TabHost changes the current tab, it kindly
// also takes care of putting focus on it when not in touch mode.
// The jerk.
// This hack tries to prevent this from pulling focus out of our
// ViewPager.
TabWidget widget = mTabHost.getTabWidget();
int oldFocusability = widget.getDescendantFocusability();
widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
mTabHost.setCurrentTab(position);
widget.setDescendantFocusability(oldFocusability);
}
public void onPageScrollStateChanged(int state)
{
}
}
}
PageOneFragment：
public class PageOneFragment extends Fragment
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.pageone_fragment, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
}
@Override
public void onAttach(Activity activity)
{
super.onAttach(activity);
}
@Override
public void onStart()
{
super.onStart();
}
@Override
public void onResume()
{
super.onResume();
}
}
PageTwoFragment
public class PageTwoFragment extends Fragment
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.pagetwo_fragment, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
}
@Override
public void onAttach(Activity activity)
{
super.onAttach(activity);
}
@Override
public void onStart()
{
super.onStart();
}
@Override
public void onResume()
{
super.onResume();
}
}
注意：调试后我注意到PageOneFragment和PageTwoFragment中的onCreateView()没有被执行。
那么发生了什么以及为什么tabHost 在导航到另一个项目后没有加载其内容？
编辑： 经过数小时痛苦的调试后，我发现我的代码在第二次调用时从未执行休闲方法：
@Override
public Fragment getItem(int position)//never get executed after the second call
{
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
我该如何解决这个问题？
非常感谢任何帮助。
提前致谢。
【问题讨论】：
-
嗨。请不要发布您的整个代码，只是为了了解您的问题。如果你能创造一个小提琴，那就太好了。
标签： java android fragment navigation-drawer android-tabhost