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ViewPager2迁移后TabLayout指示器默认消失,滑动后才显示求助

问题:ViewPager2迁移后TabLayout指示器默认不显示,滑动后正常出现

将项目从ViewPager迁移至ViewPager2后,出现如下问题:打开应用时TabLayout指示器默认不显示,但执行滑动操作后指示器会正常出现。我认为代码实现无问题,以下是简化后的Kotlin代码与XML代码:

class ScheduleWeekFragment : ScheduleBaseFragment<ScheduleWeekViewModel>(ScheduleWeekViewModel::class) {
    private val viewBinding by viewBinding(FragmentWeekBinding::bind)
    private var titles: Array<String>? = null

    // listeners
    private val viewPagerListener = object : ViewPager2.OnPageChangeCallback() {
        override fun onPageSelected(position: Int) {
            viewModel.updateDayTitle(position)
        }
    }

    // observers
    private val selectedDayObserver = Observer<Int> {
        viewBinding.viewPager2.currentItem = it
    }

    // lifecycle
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        titles = context?.resources?.getStringArray(R.array.schedule_fragment_day_abbreviations)
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
            inflater.inflate(R.layout.fragment_week, container, false)

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewBinding.viewPager2.adapter = ScheduleViewPagerAdapter(this)
        viewBinding.viewPager2.setPageTransformer(ZoomOutPageTransformer)
        TabLayoutMediator(viewBinding.tabLayout, viewBinding.viewPager2) { tab, position ->
            tab.text = titles?.getOrNull(position)
        }.attach()

        // observers
        viewModel.viewPagerPosition.observe(viewLifecycleOwner, selectedDayObserver)

        // listeners
        viewBinding.viewPager2.registerOnPageChangeCallback(viewPagerListener)
    }

    override fun onDestroyView() {
        viewBinding.viewPager2.unregisterOnPageChangeCallback(viewPagerListener)
        super.onDestroyView()
    }
}

以下是简化后的XML代码:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragmentWeek"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimary"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        style="@style/TabLayout1"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:verticalScrollbarPosition="left"
        app:layout_constraintEnd_toEndOf="@+id/viewPager2"
        app:layout_constraintStart_toStartOf="@+id/viewPager2"
        app:layout_constraintTop_toBottomOf="@+id/scheduleToolbar"
        app:tabGravity="start"
        app:tabMode="scrollable"
        android:background="@color/white"
        tools:ignore="SpeakableTextPresentCheck" />

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:background="@color/white"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tabLayout"
        tools:ignore="SpeakableTextPresentCheck" />
</androidx.constraintlayout.widget.ConstraintLayout>

内容的提问来源于stack exchange,提问作者Georgiy Chebotarev

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最近更新时间:2026.08.07 22:00:23