在ViewPager中，在滑动到第3个选项卡时，tab1中的子片段消失

Question

I have 3 tabs in a FragmentStatePagerAdapter. I have a fragment for tab 1 which adds views to its 'linearlayout' container inside a relative layout dynamically. i add dynamically some views in tab 1 fragment. I also added a complete fragment in that linearLayout container with other views up and down. this works fine.. every thing fine.

but when i go to 3rd page and come back. all views are there. but that complete fragment is vanished~~
It vanishes from tab1 and appears below the views in tab2 where another childfragment is added..

First of all i have a listFragment in tab1 and tab2. based on listItem click i load a fragment in each tab, that both fragments in tab1 and 2 inflates the same below xml and adds dynamic views, but in some case i add a complete fragment instead of a view in the linear layout given in xml. arose when i have to add two fragments in both new added fragments in tab 1 and tab2, after there were only lists, and slided to tab3. on returning back. fragment in 'tab1 main fragment' vanished and appeared below the fragment in 'tab2 main fragment'

this is the viewpager, in which i change different fragments by method setItem(fragment, position):

public static class ScreenSlidePagerAdapter extends
        FragmentStatePagerAdapter {

    public static ArrayList<Fragment> tabs_fragments = new ArrayList<Fragment>(
            3);

    public ScreenSlidePagerAdapter(FragmentManager fm,
            ArrayList<Fragment> tabs) {
        super(fm);
        ScreenSlidePagerAdapter.tabs_fragments = tabs;
    }

    @Override
    public Fragment getItem(int arg0) {
        return tabs_fragments.get(arg0);
    }

    @Override
    public int getCount() {
        return tabs_fragments.size();
    }

    @Override
    public int getItemPosition(Object object) {
        if (tabs_fragments.contains(object)) {
            return POSITION_UNCHANGED;
        }
        return POSITION_NONE;
    }

    public static void setItem(Fragment fr, int position) {
        if (position <= 2 && position >= 0) {
            tabs_fragments.remove(position);
            tabs_fragments.add(position, fr);
        } else
            Log.d("adding tab", "wrong tab position to add fragment at");
    }
}

this is how i add my fragment to linearlayout where 'll' is the linear layout inside the relative layout, that is the actual contentview for the fragment on tab1

ll.addView(getTitle("Set Message Receive Settings"));
        // View smsRecLayout = inflater.inflate(R.layout.fr_ev_sms_receive,
        // container, false);
        Bundle b = new Bundle();
        b.putInt("id", eventId);
        b.putInt("event", eventTypeId);
        Fragment fr = new FrEv_SMSReceive();
        fr.setArguments(b);
        getFragmentManager().beginTransaction()
                .add(ll.getId(), fr, "fr_sms_receive").commit();

this is the layout of fragment where another fragment is added in linear layout 'fr_event_container'. FragmentStatePagerAdapter

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".EventDetails" >

<TextView
    android:id="@+id/title"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:gravity="center_horizontal"
    android:padding="10dp"
    android:textIsSelectable="false" />

<ScrollView
    android:id="@+id/fr_event_container_scroll"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"
    android:layout_above="@+id/sep1"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/title" >

    <LinearLayout
        android:id="@+id/fr_event_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >
    </LinearLayout>
</ScrollView>

<View
    android:id="@+id/sep1"
    android:layout_width="fill_parent"
    android:layout_height="2dp"
    android:layout_above="@+id/addOther"
    android:layout_centerHorizontal="true"
    android:layout_margin="10dp"
    android:background="#000"
    android:padding="10dp"
    android:visibility="gone" />

<Button
    android:id="@+id/next"
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/addOther"
    android:layout_alignBottom="@+id/addOther"
    android:layout_alignParentRight="true"
    android:layout_marginRight="54dp"
    android:text="Next"
    android:width="90dp" />

Answer 1

The ViewPager has a maximum offscreen page limit. You can set it higher with setOffscreenPageLimit(int)

Answer 2

I have come to know that the problem was in using the same layout for both tabs without changing its Id at runtime by setId ;

Although the fragments were in different tabs but Android was treating the layout that was first added as main, so if I added a fragment in tab2 after tab1 then any thing added in tab2 or tab2 version of that layout was going in tab1(first added).

I changed layoutIds at runtime and problem is solved.