Switching orientation error: Fragment Error - Dupl

I have a Fragment SearchPageFragment (representing the main view on a tablet) which itself contains two fragments inside of it:

<fragment   android:name="com.test.fragments.SearchFormFragment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="2dp"
            android:id="@+id/searchFormFragment"
            android:tag="searchFormFragmentTag">
    <!-- Preview: layout=@layout/fragment_search_form -->
</fragment>           
<fragment   android:name="com.test.fragments.SearchResultsFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/searchResultsFragment">
    <!-- Preview: layout=@layout/fragment_search_results -->
</fragment>

Everything works fine - The page loads and everything works fine... Until you change the orientation. When you do the following error occurs:

java.lang.IllegalArgumentException: Binary XML file line #10: Duplicate id 0x7f08001f, tag searchFormFragmentTag, or parent id 0x0 with another fragment for com.test.fragments.SearchFormFragment
                                    at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:262)
                                    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563)

Here is the sequence of calls when you switch the orientation:

SearchPageFragment(4911): Creating...
SearchPageFragment(4911): Inflating...
    SearchFormFragment(4911): Creating...
    SearchFormFragment(4911): Inflating...
    SearchResultsFragment(4911): Creating...
    SearchResultsFragment(4911): Inflating...

// Change Orientation

SearchPageFragment(4911): Pausing...
    SearchFormFragment(4911): Pausing...
    SearchResultsFragment(4911): Pausing...
SearchPageFragment(4911): Destroying...
    SearchFormFragment(4911): Destroying...
    SearchResultsFragment(4911): Destroying...

// All Seems Normal - But...

SearchPageFragment(4911): Creating...
SearchPageFragment(4911): Creating...
SearchPageFragment(4911): Inflating...
    SearchFormFragment(4911): Creating...
    SearchFormFragment(4911): Inflating...
    SearchResultsFragment(4911): Creating...
    SearchResultsFragment(4911): Inflating...
SearchPageFragment(4911): Inflating...

// SearchPageFragment has started twice and crashes when the second one inflates a ***unique*** component

AndroidRuntime(4911): Shutting down VM

Does anybody know why my container Fragment would be called twice on orientation change?

回答1:

Got it:

The bug was with the holder activity for SearchPageFragment adding the Fragment twice.

Android will always retain fragments attached to a View when an orientation change occurs.

Because of this, you need to ensure that if you're adding a Fragment in your onCreate() method you surround it's creation (and addition/replacement transation) with an if statement to check that savedInstanceState is null (If it's not null it indicates an orientation change has occurred).

if(savedInstanceState == null) {
    // Add fragment code here
}

回答2:

I solved the problem using this .

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
         if (root != null) {
                ViewGroup parent = (ViewGroup) root.getParent();
                if (parent != null)
                    parent.removeView(root);
            }
            try {
                root = inflater.inflate(R.layout.activity_explore,container,false);
            } catch (InflateException e) {
                /* map is already there, just return view as it is */
            }
 return root;
}