Develop Reference

Going back to fragment second time using tabs shows blank fragment

I have 2 tabs in my app, using tablistner and I'm facing an issue when I'm navigating in a very specific situation to other tab and then navigating back to the first tab.
It happens after i load a fragment called "setFrom" from another fragment:
public void LoadSetFrom ()
{
final FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
SherlockFragment setFrag = new setFrom();
ft.replace(R.id.main_layout, setFrag, "setfrom");
ft.commit();
}
This "setFrom" fragment is one of my 2 tabs, after that I'm navigatin to the second tab and when I'm going back to "setFrom" the tabs navigation still appears but the fragment is totally blank.
I'm using TabListener that way:
public class TabListener<T extends SherlockFragment> implements com.actionbarsherlock.app.ActionBar.TabListener
{
private SherlockFragment mFragment;
private setFrom fromFragment;
private final SherlockFragmentActivity mActivity;
private final String mTag;
private final Class<T> mClass;
public TabListener(SherlockFragmentActivity activity, String tag, Class<T> clz) {
mActivity = activity;
mTag = tag;
mClass = clz;
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
SherlockFragment preInitializedFragment = (SherlockFragment)mActivity.getSupportFragmentManager().findFragmentByTag(mTag);
if (preInitializedFragment == null) {
mFragment = (SherlockFragment) SherlockFragment.instantiate(mActivity, mClass.getName());
ft.add(R.id.main_layout, mFragment, mTag);
}
else {
ft.attach(preInitializedFragment);
}
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null)
ft.detach(mFragment);
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
}
After checking onTabSelected, "setFrom" is not null,it attached to the right fragment and it goes to ft.attach(preInitializedFragment) which is fine.
My question is why after the attach to the right fragment the view is still blank?

I was facing the same problem
Solved it by adding setRetainInstance(true); to my Fragment's onCreate

Hiding/Showing SherlockFragments in ActionBar.TabListener Class, content is empty

I have an app built using TabBarSherlock and the Support library to add ActionBar support to pre 3.0 devices. I can't remember what tutorial I followed to create the Tabs and the Listener but I have the following code.
Firstly creating the Tabs (Inside a SherlockFragmentActivity):
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayShowTitleEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
/*--------Setup News Tab--------*/
Tab tab1 = actionBar.newTab()
.setText("News")
.setTabListener(new TabListener<TabFragment>(
this, "tab1", TabFragment.class));
Bundle newsBundle = new Bundle();
newsBundle.putInt("news_id", newsID);
tab1.setTag(newsBundle);
actionBar.addTab(tab1);
/*------------------------------*/
// This is repeated 3 more times to total 4 Tabs.
Then I have a classCalled TabListener which is used in each of these Tabs to detect when they have been selected.
public class TabListener<T extends Fragment> implements ActionBar.TabListener{
private TabFragment mFragment;
private final Activity mActivity;
private final String mTag;
private final Class<T> mClass;
public TabListener(Activity activity, String tag, Class<T> clz) {
mActivity = activity;
mTag = tag;
mClass = clz;
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// Check if the fragment is already initialised
if (mFragment == null) {
Log.v("FRAGMENT", "FRAGMENT NEEDS TO BE CREATED");
mFragment = (TabFragment) Fragment.instantiate(mActivity, mClass.getName(), (Bundle)tab.getTag());
ft.add(android.R.id.content, mFragment, mTag);
} else {
Log.v("FRAGMENT", "FRAGMENT ALREADY CREATED");
ft.show(mFragment);
}
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null) {
ft.hide(mFragment);
}
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
}
With the class TabFragment containing a ViewPager for each Tab. My issue is that when selecting a Tab other than the first one the content inside the Fragment does not show. From the logs in place when the Fragment is initialised I can tell the views are being created just not being shown, it's just a blank area showing the background.

Instead of using show() and hide(), use attach() and detach(). Using show/hide does not remove the view hierarchy from the screen, simply hides it, so there might be issues related to that.

You are not detaching fragment rather you are just hiding it. so you should detach it so that other fragment should be attached in your onTabUnSelected.
FragmentManager will automatically restore whatever fragment (and history) was currently displayed upon a configuration change. Call findFragmentByTag to see if an instance of the target fragment already exists before creating and attaching a new instance.
Example:
public void onTabSelected(Tab tab, FragmentTransaction ft) {
SherlockFragment preInitializedFragment = (SherlockFragment) mActivity.getSupportFragmentManager().findFragmentByTag(mTag);
// Check if the fragment is already initialized
if (mFragment == null && preInitializedFragment == null) {
// If not, instantiate and add it to the activity
mFragment = (SherlockFragment) SherlockFragment.instantiate(mActivity, mClass.getName());
ft.add(android.R.id.content, mFragment, mTag);
} else if (mFragment != null) {
// If it exists, simply attach it in order to show it
ft.attach(mFragment);
} else if (preInitializedFragment != null) {
ft.attach(preInitializedFragment);
mFragment = preInitializedFragment;
}
}
and you onTabUnSelected should be like this
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null) {
// Detach the fragment, because another one is being attached
ft.detach(mFragment);
}
}

Content is empty on tab bar then write below code
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(actionBar.NAVIGATION_MODE_STANDARD);

onCreateView not called for tabs in actionbar TabsAdapter for second time tab selected?

I have a tabbed application built with fragments and ActionBarSherlock. I have 3 tabs, with 3 ListFragment's Here's what's happening.
When I select any tab, the onCreate method for the associated fragment is called as expected at first time but not at second. The problem is that the onCreate method is called for the next adjacent tab but not selected tab.
Click on tab2 and onCreate of tab3 is called but not tab2.
Actually my requirement is, when i change some data in tab1 means fragment1. those changes are not effected in fragment2, when i select tab2 (fragment2) it means fragment2 onCreate() was not calling. why it's not refreshing the fragment properly. this is the adapter i am using.
private class TabsAdapter extends FragmentPagerAdapter implements ViewPager.OnPageChangeListener, ActionBar.TabListener {
public TabsAdapter(FragmentActivity activity, ActionBar actionBar, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = actionBar;
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
public void addTab(ActionBar.Tab tab, Class<?> clss, int tabId) {
mTabs.add(clss.getName());
mTabsId.add(tabId);
mActionBar.addTab(tab.setTabListener(this));
notifyDataSetChanged();
}
public Integer getIdForPosition(int position) {
if (position >= 0 && position < mTabsId.size()) {
return mTabsId.get(position);
}
return null;
}
#Override
public int getCount() {
return mTabs.size();
}
#Override
public Fragment getItem(int position) {
//TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, mTabs.get(position), new Bundle());
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
Log.i(TAG, "*******tab selected*******" +tab);
clearDetails();
if (mViewPager.getCurrentItem() != tab.getPosition()) {
mViewPager.setCurrentItem(tab.getPosition(), true);
}
}
#Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
if (mCurrentPosition == position) {
}
mNextPosition = position;
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}

From this page:
The fragment of each page the user visits will be kept in memory,
though its view hierarchy may be destroyed when not visible.
This means that your fragments that are not visible to the user are still being kept in memory, so their onCreate methods won't be called when they're redisplayed. You can force them to be kicked out of memory when you switch pages by setting the ViewPager's offscreen page limit to 0.
A better way might be to use some sort of external data model shared between your Fragments and then use your onPageSelected method to tell the Fragment to update itself based on the data model when brought into view.

when you are on a Tab:(n), only Tab:(n-1) and Tab:(n+1) will be alive in the memory, for memory usage optimization. Rest all Tabs will be destroyed, thats the reason why when you come back to the first Tab, its onCreateView is being called again.
Actually Tab:1's onCreateView will be called even if you click Tab:2 because its the neighbourhood Tab.
One solution i got is:
change the OffscreenPageLimit of the ViewPager. Its default value is 1
Try changing it to 0. Should work.But in case if it didn't
Use the Call backs
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}

Replacing Fragment in tab, changes all tabs

EDIT
I edited the previous question, wich i solved. Thanks a lot for the replies.
I have a gui with 3 tabs (News, Strategy and History), in one of them (News) i load an ExpandableListView and when the user clicks in one of the items from the list, it loads another fragment containg details from the selected item. I managed to replace the fragment in that tab with another fragment, using this code:
CategoryTab categories = new CategoryTab();//Fragment 2
FragmentManager manager = activity.getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(this.getId(), categories, "News");
//transaction.replace(android.R.id.content, categories, "News");
transaction.addToBackStack(null);
transaction.commit();
When the seconds fragment loads in the News tab, all the other tabs shows that fragment. I'm using this listener to manage tab navigation
public static class TabListener<T extends Fragment> implements ActionBar.TabListener {
private final Activity mActivity;
private final String mTag;
private final Class<T> mClass;
private final Bundle mArgs;
private Fragment mFragment;
public TabListener(Activity activity, String tag, Class<T> clz) {
this(activity, tag, clz, null);
}
public TabListener(Activity activity, String tag, Class<T> clz, Bundle args) {
mActivity = activity;
mTag = tag;
mClass = clz;
mArgs = args;
// Check to see if we already have a fragment for this tab, probably
// from a previously saved state. If so, deactivate it, because our
// initial state is that a tab isn't shown.
mFragment = mActivity.getFragmentManager().findFragmentByTag(mTag);
if (mFragment != null && !mFragment.isDetached()) {
FragmentTransaction ft = mActivity.getFragmentManager().beginTransaction();
ft.detach(mFragment);
ft.commit();
}
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if (mFragment == null) {
mFragment = Fragment.instantiate(mActivity, mClass.getName(), mArgs);
ft.add(android.R.id.content, mFragment, mTag);
} else {
ft.attach(mFragment);
}
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null) {
ft.detach(mFragment);
}
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
Toast.makeText(mActivity, "Reselected!", Toast.LENGTH_SHORT).show();
}
}
My question is ¿why all the tabs shows the same fragment when the replacement is done? and ¿how can i simulate a back button with the icon provided in the action bar, to load again fragment 1 in News Tab?
Any help will be appreciated
PD: Sorry for my english

Make sure you call getActivity() in or after onActivityCreated, as before then it will return null.
The Fragment will be attached to a null activity until onActivityCreated... that is, if you call getActivity() in onCreate or onCreateView, it will return null because the Activity hasn't been created yet. So make sure you have all of your calls to getActivity() in or after onActivityCreated

Action Bar Tabs - Having two fragments (one being dynamic) in one tab

I am trying to create a tab that displays a list on the left hand fragment and a detailed fragment on the right. When a user clicks a list item, the right hand fragment should change to the appropriate one.
I am new to android so I used a tutorial and I know I need to do something with the tablistener: public static class TabListener implements ActionBar.TabListener
{
private final Activity mActivity;
private final String mTag;
private final Class mClass;
private final Bundle mArgs;
private Fragment mFragment;
public TabListener(Activity activity, String tag, Class<T> clz) {
this(activity, tag, clz, null);
}
public TabListener(Activity activity, String tag, Class<T> clz, Bundle args) {
mActivity = activity;
mTag = tag;
mClass = clz;
mArgs = args;
// Check to see if we already have a fragment for this tab, probably
// from a previously saved state. If so, deactivate it, because our
// initial state is that a tab isn't shown.
mFragment = mActivity.getFragmentManager().findFragmentByTag(mTag);
if (mFragment != null && !mFragment.isDetached()) {
ft = mActivity.getFragmentManager().beginTransaction();
ft.detach(mFragment);
ft.commit();
}
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if (mFragment == null) {
mFragment = Fragment.instantiate(mActivity, mClass.getName(), mArgs);
ft.add(android.R.id.content, mFragment, mTag);
tabtag = mTag;
}
else {
ft.attach(mFragment);
}
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
if (mFragment != null) {
ft.detach(mFragment);
}
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
//Toast.makeText(mActivity, "Reselected!", Toast.LENGTH_SHORT).show();
}
}
Another good example of what I need would be something like the Gmail app, with a list on the left, detail on the right, and keeping the action bar (mine has tabs) on top.
I understand that this listener inflates a fragment for each tab clicked, but how do I inflate a layout that has two fragments in it?

Inflating a layout with two fragments is simple: you just specify the Class of each fragment in the layout. But you can't mix static (layout XML-defined) and dynamic Fragments. By which I mean, you can't dynamically instantiate a new Fragment in code and insert it into a View container (e.g., a LinearLayout) that was originally populated with Fragments in the XML.