Android TabLayout prevent activation of tabs adjacent to selected

2018-07-12 00:54 William Jockusch imported from Stackoverflow

I have a tab-based app. I am using A TabLayout for my tabs and a subclass of FragmentStatePagerAdapter to instantiate the fragment for the selected tab. I have disabled swiping between tabs. I am still seeing a callback to create a fragment for tabs adjacent to the selected tab. In other words, if the tab at index 0 is activated, I also see a callback to GetItem for the tab at index 1.

I want to disable that behaviour. In other words, it should only request a fragment for the active tab. Is that possible?

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/root">
    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabPaddingStart="0dp"
        app:tabPaddingEnd="0dp"
        app:tabPaddingTop="0dp"
        app:tabMode="fixed"
        app:tabGravity="fill" />
    <jockusch.calculator.droid.AndroidViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

2 answers

answered 2018-07-12 01:09 RoyalGriffin
```
viewPager.setOffscreenPageLimit(0)
```
is what you are looking for. But a ViewPager doesn't allow offscreen limit less than 1.

source

Use something else than a viewPager to get your desired effect. One way of doing it without viewPager would be to have a frameLayout instead and inflate a new fragment and destroy the previous one when a tab is selected.
answered 2018-07-12 01:12 Jackey
The reason this is happening is due to you using a ViewPager.

ViewPager, by default, will auto-create the adjacent Fragments because this allows the user to swipe to them whenever they wish. Creating them only when they're ready to swipe might cause lag or some unpleasant visual effects.

ViewPager has a method called setOffscreenPageLimit(int limit) which can limit the amount of adjacent it keeps in memory, however I believe it's not possible to decrease it to 0 due to ViewPager's innate behavior.

If you've already disabled swiping between tabs, then it sounds like what you want isn't a ViewPager. Consider just using FragmentTransactions to replace the active Fragment.

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I'm a creating a app with navigation Drawer and TabLayout. I created the navigation Drawer and added the TabLayout, each tab is supossed to have a fragmente, but the fragment isn't appearing, it's like the Draweaver is "covering" them. Does someone knows what's my mistake here?

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public class Home extends AppCompatActivity


        implements NavigationView.OnNavigationItemSelectedListener {


    FirebaseAuth mAuth;
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    private PagerAdapter adapter;
    private ViewPager viewPager;


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XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
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    xmlns:tools="http://schemas.android.com/tools"
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        android:layout_height="match_parent" />

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        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_home"
        app:menu="@menu/activity_home_drawer" />

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The fragments are added on this XML that are the app_bar_home

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
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    xmlns:tools="http://schemas.android.com/tools"
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    android:layout_height="match_parent"
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        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">


        <android.support.v7.widget.Toolbar
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            android:id="@+id/viewpager_id"></android.support.v4.view.ViewPager>



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    private final List<String> listTitle = new ArrayList<>();



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Fragmento 1

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    }


    @Nullable
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XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimary">

    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/anuncio_reciclerview">

    </android.support.v7.widget.RecyclerView>

</android.support.constraint.ConstraintLayout>

fragmento 2

public class PedidoFragmento extends Fragment {

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    public PedidoFragmento() {
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    @Nullable
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<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
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        android:layout_height="match_parent"
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