Hey there, let's dig into why your Fragments aren't showing up with that layout setup. I've run into similar snags before, so here are the most common checks you should walk through:

This is the #1 culprit for missing Fragments 9 times out of 10. Make sure you've properly bound a FragmentPagerAdapter or FragmentStatePagerAdapter to your NonSwipeableViewPager, and that the adapter correctly returns your Fragment instances.

For example, a basic adapter implementation might look like this (Kotlin):

class MyPagerAdapter(fragmentManager: FragmentManager) :
    FragmentPagerAdapter(fragmentManager, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {

    override fun getCount(): Int = 2 // Match your 2 Fragments

    override fun getItem(position: Int): Fragment {
        return when(position) {
            0 -> FirstFragment()
            1 -> SecondFragment()
            else -> FirstFragment() // Fallback
        }
    }
}

And don't forget to attach it to your ViewPager in your Activity/Fragment:

// If in an Activity
viewpager.adapter = MyPagerAdapter(supportFragmentManager)

// If in a parent Fragment
viewpager.adapter = MyPagerAdapter(childFragmentManager)

Your ViewPager has android:layout_height="match_parent" paired with android:layout_above="@+id/tabs" — this can cause layout overlap or the ViewPager getting squeezed out entirely if your tabs component isn't configured correctly.

• Ensure your tabs (likely a TabLayout) is anchored to the bottom with a fixed/ wrapable height:

  <com.google.android.material.tabs.TabLayout
      android:id="@+id/tabs"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:background="@color/your_tab_bg_color"/>
  

• If your tabs had android:layout_height="match_parent", it would take up the entire screen, pushing the ViewPager out of view.

Sometimes the issue isn't the ViewPager — it's the Fragment itself. Test if your Fragment's layout is rendering at all by adding a bright background color to its root layout:

<!-- Inside your Fragment's layout file -->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/bright_red"> <!-- Add this -->
    <!-- Rest of your Fragment content -->
</LinearLayout>

If you still don't see the red background, the problem is with the ViewPager/Adapter. If you do see it, debug your Fragment's internal views (e.g., check if views are set to visibility="gone" or have no content).

Custom ViewPager implementations can accidentally break core functionality. Try temporarily replacing NonSwipeableViewPager with the standard ViewPager (or ViewPager2) and see if your Fragments appear. If they do, your custom class has a bug — check if you've overridden onTouchEvent or onInterceptTouchEvent in a way that blocks normal ViewPager loading logic.

Open Logcat and filter for keywords like "Fragment" or "ViewPager". Look for exceptions like:

• Fragment instantiation failures
• Adapter binding errors
• Layout inflation issues
  These logs will often point you directly to the root cause.

内容的提问来源于stack exchange，提问作者Alsong Dun Dunstan Philander