Tabs in Android action bar - problems with internal transaction fragmentation

Question

I successfully configured the tabs in the action bar using the following example from Google itself: http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/FragmentTabs.html as grounds. My code looks like this:

public class Main extends SherlockFragmentActivity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getSupportActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); ActionBar.Tab tab1 = getSupportActionBar().newTab(); tab1.setIcon(R.drawable.ic_tab_example_selected); tab1.setTabListener(new TabListener<Tab1>(this, "A", Tab1.class)); getSupportActionBar().addTab(tab1); ActionBar.Tab tab2 = getSupportActionBar().newTab(); tab2.setIcon(R.drawable.ic_tab_example_selected); tab2.setTabListener(new TabListener<Tab2>(this, "B", Tab2.class)); getSupportActionBar().addTab(tab2); ActionBar.Tab tab3 = getSupportActionBar().newTab(); tab3.setIcon(R.drawable.ic_tab_example_selected); tab3.setTabListener(new TabListener<Tab3>(this, "C", Tab3.class)); getSupportActionBar().addTab(tab3); ActionBar.Tab tab4 = getSupportActionBar().newTab(); tab4.setIcon(R.drawable.ic_tab_example_selected); tab4.setTabListener(new TabListener<Tab4>(this, "D", Tab4.class)); getSupportActionBar().addTab(tab4); } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getSupportMenuInflater(); inflater.inflate(R.menu.menu, menu); return true; } public class TabListener<T extends Fragment> implements ActionBar.TabListener { private Fragment mFragment; private final SherlockFragmentActivity mActivity; private final String mTag; private final Class<T> mClass; /** Constructor used each time a new tab is created. * @param activity The host Activity, used to instantiate the fragment * @param tag The identifier tag for the fragment * @param clz The fragment Class, used to instantiate the fragment */ public TabListener(SherlockFragmentActivity activity, String tag, Class<T> clz) { mActivity = activity; mTag = tag; mClass = clz; } /* The following are each of the ActionBar.TabListener callbacks */ public void onTabSelected(Tab tab, FragmentTransaction ft) { // Check if the fragment is already initialized if (mFragment == null) { // If not, instantiate and add it to the activity mFragment = Fragment.instantiate(mActivity, mClass.getName()); ft.add(android.R.id.content, mFragment, mTag); } else { // If it exists, simply attach it in order to show it ft.attach(mFragment); } } public void onTabUnselected(Tab tab, FragmentTransaction ft) { if (mFragment != null) { // Detach the fragment, because another one is being attached ft.detach(mFragment); } } public void onTabReselected(Tab tab, FragmentTransaction ft) { // User selected the already selected tab. Usually do nothing. } } } 

In doing so, I have several tabs that switch between different fragments on each tab. However, my problem starts when the tab and change fragments from the tab. This is problem:

When I am in Tab 1 , I replace the initial fragment loaded on the tab with a new fragment. Then I go to Tab 2, which shows its initial fragment. However, the view of the fragment that has changed on tab 1 is still displayed behind the fragment of Tab 2 :

This is the code I'm currently using to change the snippet from tab 1 :

 // Create new fragment and transaction FragmentTransaction transaction = ctx.getFragmentManager().beginTransaction(); transaction.setCustomAnimations(R.anim.slide_in_left, R.anim.slide_out_right); // Replace whatever is in the fragment_container view with this fragment, // and add the transaction to the back stack transaction.replace(container, fragment, tag); if(addToBackStack) transaction.addToBackStack(tag); // Commit the transaction transaction.commit(); 

All this is done through the ActionBar Sherlock and in the Google v4 support library.

Answer 1

So this answer assumes that you want to erase every bookmark history every time you change tabs. I mean, Tab 1 starts with fragment 1, then you press and change it to frag 2. If you select Tab 2, you cancel the history of Tab 1, and the next time you press Tab 1, you will return to frag 1.

With that said, there will be a solution here: replace your onTabUnselected below

 public void onTabUnselected(Tab tab, FragmentTransaction ft) { if (mFragment != null) { //this segment removes the back history of everything in the tab you are leaving so when you click on the tab again you go back to a fresh start FragmentManager man = mActivity.getFragmentManager(); if(man.getBackStackEntryCount()>0) //this check is required to prevent null point exceptions when clicking off of a tab with no history man.popBackStack(man.getBackStackEntryAt(0).getName(), FragmentManager.POP_BACK_STACK_INCLUSIVE); //this pops the stack back to index 0 so you can then detach and then later attach your initial fragment //also it should be noted that if you do popbackstackimmediate here instead of just popbackstack you will see a flash as the gui changes back to the first fragment when the code executes //end ft.detach(mFragment); } }