FragmentStateAdapter抛出java.lang.IllegalStateException：配置更改后违反设计假设

Question

FragmentStateAdapter抛出

java.lang.IllegalStateException： Design Assumption 违反了，

当设备旋转时。如何解决此问题？

private inner class PagerAdapter : FragmentStateAdapter(this) {
        private val ids = LongSparseArray<Media>()

        override fun getItemCount(): Int = adapter.itemCount

        override fun getItemId(position: Int): Long {
            return adapter.source!![position].time
        }

        override fun containsItem(itemId: Long): Boolean {
            return ids[itemId] != null
        }
    }

例外

 java.lang.IllegalStateException: Design assumption violated.
        at androidx.viewpager2.adapter.FragmentStateAdapter.placeFragmentInViewHolder(FragmentStateAdapter.java:270)
        at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:259)
        at androidx.viewpager2.adapter.FragmentStateAdapter.onViewAttachedToWindow(FragmentStateAdapter.java:68)

Answer 1

此问题现已在ViewPager2中修复

您需要使用版本 1.0.0-beta03

更新 ViewPager2 的依赖项

 dependencies {
    implementation 'androidx.viewpager2:viewpager2:1.0.0-beta03'
 }

错误修复

• 修复了具有暂时性片段状态的片段状态Adapter 问题。 b/134246546

Answer 2

我找到了解决办法。显然，为了正确恢复片段，您必须在other中的配置发生更改后恢复FragmentStateAdapter的状态。

拯救国家

override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        model.addState(IDS, pagerAdapter.ids)
        model.addState(LIST, (adapter.source as ListAdapterSource).getList())
    }

恢复状态

private inner class PagerAdapter : FragmentStateAdapter(this) {
        val ids: LongSparseArray<Media> = model.getState(IDS) ?: LongSparseArray()
        ...
}