IllegalStateException: Can't change container ID of Fragment

Question

Android platform: 3.1 I am trying to move a fragment from a container A to a container B. Here follows the code to accomplish this: ``` private void reattach(int newContainerId, Fragment frag, String tag) { if (frag == null || !frag.isAdded() || (frag.getId() == newContainerId)) { return; } final FragmentManager fm = getFragmentManager(); FragmentTransaction ft = fm.beginTransaction(); ft.remove(frag); //stacco il frammento dal container A ft.commit(); fm.executePendingTransactions(); ft = fm.beginTransaction(); ft.add(newContainerId, frag, tag); //attacco il frammento sul container D ft.commit(); fm.executePendingTransactions(); } ``` When I run the system, I get the following IllegalStateException: ``` 03-26 00:13:14.829: E/AndroidRuntime(30090): java.lang.RuntimeException: Unable to start activity ComponentInfo{eu.areamobile.apps.sfa/eu.areamobile.apps.sfa.activity.HomeActivity}: java.lang.IllegalStateException: Can't change container ID of fragment FragmentHomeController{408202a8…

Accepted Answer

My solution to this problem is to re-create the fragment while keeping its state:

```
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.remove(old);
Fragment newInstance = recreateFragment(old);
ft.add(R.id.new_container, newInstance);
ft.commit();
```

With the following helper function:

```
private Fragment recreateFragment(Fragment f)
    {
        try {
            Fragment.SavedState savedState = mFragmentManager.saveFragmentInstanceState(f);

Fragment newInstance = f.getClass().newInstance();
            newInstance.setInitialSavedState(savedState);

return newInstance;
        }
        catch (Exception e) // InstantiationException, IllegalAccessException
        {
            throw new RuntimeException("Cannot reinstantiate fragment " + f.getClass().getName(), e);
        }
    }
```

It works for me, at least with the latest support library (r11), although I didn't test much yet.

The extra cost is to instantiate the fragment twice.

IllegalStateException: Can't change container ID of Fragment

Solution

Problem

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