IllegalStateException: Fragment already added in the tabhost fragment

问题

FATAL EXCEPTION: main
Process: com.example.loan, PID: 24169
java.lang.IllegalStateException: Fragment already added: FormFragment{428f10c8 #1 id=0x7f050055 form}
    at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1192)
    at android.support.v4.app.BackStackRecord.popFromBackStack(BackStackRecord.java:722)
    at android.support.v4.app.FragmentManagerImpl.popBackStackState(FragmentManager.java:1533)
    at android.support.v4.app.FragmentManagerImpl$2.run(FragmentManager.java:489)
    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1484)
    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:450)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:136)
    at android.app.ActivityThread.main(ActivityThread.java:5068)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
    at dalvik.system.NativeStart.main(Native Method)

So, I have an android app that build with the tabhost. There are three tabs in total, in the tab2, there is a button to make the fragment transaction in tab2 (which is calling the function in the fragment activity)

FragmentTransaction t = getSupportFragmentManager().beginTransaction();
        t.replace(R.id.realtabcontent, mFrag);
        t.addToBackStack(null);
        t.commit();

There is exception if I run like this:

1. Inside the tab2, I press the button to change fragment
2. Go to other tab (eg. tab 1 or tab 3)
3. Press back button
4. Throw exception

How to fix that? Thanks for helping

回答1:

This happens when we try to add same fragment or DialogFragment twice before dismissing,

just call

if(mFragment.isAdded())
{
     return; //or return false/true, based on where you are calling from
}

Having said that, I don't see any reason why to remove old fragment and add the same fragment again since we can update the UI/data by simply passing parameters to the method inside the fragment

回答2:

Remove the old fragment in case it is still added and then add the new fragment:

FragmentManager fm = getSupportFragmentManager();
Fragment oldFragment = fm.findFragmentByTag("fragment_tag");
if (oldFragment != null) {
    fm.beginTransaction().remove(oldFragment).commit();
}
MyFragment newFragment = new MyFragment();
fm.beginTransaction().add(newFragment , "fragment_tag");

回答3:

You just have to check one condition in your fragment mentioned below:

if(!isAdded())
{
    return;
}

isAdded = Return true if the fragment is currently added to its activity. Taken from the official document. This will not add that fragment if it is already added

Check below link for a reference:
http://developer.android.com/reference/android/app/Fragment.html#isAdded()

回答4:

You just have to check one condition before start fragment transaction

 if (!fragmentOne.isAdded()){
            transaction = manager.beginTransaction();
            transaction.add(R.id.group,fragmentOne,"Fragment_One");
            transaction.commit();
 }

this is working perfactly for me...

回答5:

Sometimes it happens for not finding proper id from the respective layout. I faced this problem. Then after many hours I found that I set wrong recyclerview id. I change it, and works fine for me.

So, double check your fragment layout.

回答6:

For me it works like:

Fragment oldFragment = manager.findFragmentByTag(READER_VIEW_POPUP);
if (oldFragment != null) {
    manager.beginTransaction().remove(oldFragment).commit();
}

FragmentTransaction ft = manager.beginTransaction();
ft.add(this, tag);
ft.commit();

回答7:

It even can occur if in FragmentStatePagerAdapter of your ViewPager you create an item that already exists:

override fun getItem(position: Int): Fragment {
    return tabs[0] // Right variant: tabs[position]
}

(private val tabs: List<Fragment> is a list of fragments in tabs).

回答8:

To my surprise, I made stupid mistake by calling the fragment transaction twice:

if (!FirebaseManager.isClientA && !FirebaseManager.isClientB) {
      fragment = new FragmentA();
      getFragmentManager().beginTransaction().add(R.id.fragment_frame, fragment, null).addToBackStack("").commit();
} else if (FirebaseManager.isClientB) {
      fragment = new FragmentB();
} else {
      fragment = new FragmentC();
}
getFragmentManager().beginTransaction().add(R.id.fragment_frame, fragment, null).addToBackStack("").commit();

Make sure you don't make the same mistake.

回答9:

Add Fragment as below

FragmentTransaction t = getSupportFragmentManager().beginTransaction();
    t.replace(R.id.realtabcontent, mFrag);
    t.addToBackStack(null);
    t.commitNowAllowingStateLoss();

回答10:

You can try this:

 if (dialogFolderGallery.isAdded()) {
                dialogFolderGallery.dismiss();
            } else { //bla...bla..
}

来源：https://stackoverflow.com/questions/25926402/illegalstateexception-fragment-already-added-in-the-tabhost-fragment