查看片段中的分页器

Question

I have bottom navigation bar implemented with view pager. Now on the first fragment I want tabs on the top so I need a view pager inside of that fragment only. That view pager will have its own set of fragments. Is it possible? Can some one help me do it?

Answer 1

Yes, it is completely possible since your inner viewpager and tablayout will be independent from its parent fragment. The process to achieve this is exactly the same you used to create your first set of tabs, but you have to use getChildFragmentManager() instead:

getChildFragmentManager().beginTransaction().add(R.id.yourinnercontainer, YourFragment.newInstance()).commit();
getChildFragmentManager().executePendingTransactions();

And for the TabLayout just create your views and use the setupWithViewPager(viewPager) function as usual.

Answer 2

Yes you can add viewPager to the XML of your fragment like this:

<android.support.design.widget.AppBarLayout
    android:id="@+id/app_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layoutDirection="ltr"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:contentInsetEnd="16dp"
        app:popupTheme="@style/AppTheme.PopupOverlay">

        <TextView
            android:id="@+id/toolbar_title"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="start|center_vertical"
            android:gravity="center|start"
            android:text="@string/app_name"
            android:textAppearance="@style/TextAppearance.AppCompat.Title"/>
    </android.support.v7.widget.Toolbar>

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        app:tabIndicatorHeight="3dp"
        app:tabMode="fixed"/>
</android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

and manage it in your code like this:

        ViewPager pager = (ViewPager) findViewById(R.id.pager);
    mAdapter = new MyPagerAdapter(getSupportFragmentManager());

    mAdapter.addFragment(first_fragment, firts_fragment_title);
    mAdapter.addFragment(second_fragment, second_fragment_title);
    pager.setAdapter(mAdapter);

    TabLayout tabs = (TabLayout) findViewById(R.id.tabs);
    tabs.setupWithViewPager(pager);
    TextView first_fragment_tab = (TextView) getLayoutInflater().inflate(R.layout.tab_indicator, null);
    TextView second_fragment_tab = (TextView) getLayoutInflater().inflate(R.layout.tab_indicator, null);

    tabs.getTabAt(0).setCustomView(first_fragment_tab);
    tabs.getTabAt(1).setCustomView(second_fragment_tab);
    pager.setCurrentItem(mAdapter.getCount());

Answer 3

Nested Fragment is possible. But Fragment tends to bring new sets of troubles, so with integration of another Fragment layer on top of it, we might end up in deep trouble. If you are performing basic operations, it might be OK but if there is cases of data exchanges and other inter fragments dependency, I would suggest to be very careful.

Answer 4

Yes, it is possible!

Step 1: Create Tabbed activity. (It will automatically create an activity with ViewPager)

Step 2: Convert that activity to a fragment to be able add it to your BottomNavigation. Use this answer: Converting activity to fragment

Note: I did this in a project and having other ViewPager s on other tabs of BottomNavigation bar made every a bit more complicated. Using viewPager.setOffscreenPageLimit(...); will solve some of your possible problem.