Java TabHost只显示一次内容(onCreate)
我在Java TabHost只显示一次内容(onCreate),java,android,fragment,navigation-drawer,android-tabhost,Java,Android,Fragment,Navigation Drawer,Android Tabhost,我在navigationDrawer中有一个TabHost,当我从作为导航抽屉项存在的TabHost转到另一个导航抽屉项并返回到TabHost时,会遇到一个奇怪的问题,它不会显示其内容,第一次它工作得很好,但当我更改项目并返回时,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(带内容)时它的外观如何 转到另一个navDrawer项目并返回TabHost后 public class PageTwoFragment extend
navigationDrawer
中有一个TabHost
,当我从作为导航抽屉项存在的TabHost
转到另一个导航抽屉项并返回到TabHost
时,会遇到一个奇怪的问题,它不会显示其内容,第一次它工作得很好,但当我更改项目并返回时,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(带内容)时它的外观如何
转到另一个navDrawer项目并返回TabHost后
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();
}
}
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)
{
}
}
}
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()
没有执行
那么发生了什么,为什么tabHost
在导航到另一个项目后不加载其内容呢
编辑:
经过数小时痛苦的调试后,我发现我的代码从未对第二次调用执行fallowing方法,即:
@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);
}
我怎样才能解决这个问题
非常感谢您的帮助
提前谢谢。这个可笑的错误花费了我很多时间,虽然解决方法其实很简单,但问题是我用的是
FragmentPagerAdapter
而不是FragmentStatePagerAdapter
替换后,一切都很好,希望这将有助于解决类似问题。在您的代码中,碎片页面适配器
将使用活动的碎片管理器
,但当在碎片页面适配器
中实例化Item
时,它将在活动的碎片管理器
中找到碎片。不幸的是,PageOneFragment
和pagetworfragment
已经在活动的FragmentManager
中,因此没有新的创建PageOneFragment
和pagetworfragment
,FragmentPageAdapter
将在片段backbackback中使用PageOneFragment
。但是PageOneFragment
被添加到最后一个FragmentPageAdapter
中,然后就没有内容了
使用FragmentPageStateAdapter替换FragmentPageAdapter是一个简单的选择。如果您想在某些时候使用比FragmentPageStateAdapter
更好的FragmentPageAdapter
,您可以这样使用它:
public TabsAdapter(Fragment fragment, TabHost tabHost, ViewPager pager)
{
super(fragment.getChildFragmentManager());
mContext = fragment.getActivity();
mTabHost = tabHost;
mViewPager = pager;
mTabHost.setOnTabChangedListener(this);
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
Log.i("Test", "TabsAdapter super");
}
使用ChildFragmentManager
我认为,如果您删除活动的
FragmentManager
中的PageOneFragment
和pagetworfragment
,也可以 嗨。请不要发布你的全部代码,只是为了理解你的问题。如果你能做一把小提琴那就太好了。我两天前也遇到了同样的情况!对我来说也花了很多时间!!两天前,我才在另一篇SO帖子上找到了这个解决方案!是的,这太荒谬了!(这是我的问题!)