[英]cannot restore recyclerview scroll position after rotation
我制作了一個 recyclerview 網格,一旦用戶按下按鈕,就會填充來自 api 的數據。 旋轉屏幕后,滾動 position 會短暫恢復,然后再向上滾動到網格頂部。 我正在使用本教程來保存我的卷軸 position:
class MainActivity : AppCompatActivity(), Main.View {
private lateinit var carAdapter: CarAdapter
private lateinit var presenter: Main.MainPresenter
private lateinit var cars: ArrayList<Car?>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
carsAdapter = CarsAdapter(mutableListOf())
// line suggested by androiddevelopers article
carsAdapter.stateRestorationPolicy =
RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY
gridRV.layoutManager = GridLayoutManager(this, 3)
gridRV.adapter = carsAdapter
if (savedInstanceState != null) {
cars = savedInstanceState.getParcelableArrayList<Car?>(CARS_ARG)
as ArrayList<Car?>
carsAdapter.cars = cars
carsAdapter.notifyDataSetChanged()
}
presenter = Main.MainPresenter(this, CarService(R.string.api_ul))
search_button.setOnClickListener { presenter.onSearchClick() }
}
// presenter.onSearchClick() calls this
override fun displayGrid() {
this.cars = cars
carsAdapter.cars = cars
carsAdapter.notifyDataSetChanged()
}
override fun onSaveInstanceState(outState: Bundle) {
super.onSaveInstanceState(outState)
outState.putParcelableArrayList(CARS_ARG, cars)
}
}
我還嘗試在本教程中保存布局 state。
我的清單條目是:
<activity
android:name=".main.MainActivity"
android:launchMode="singleTop">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
那么屏幕旋轉是一種配置更改,它會導致活動重新創建,因此您會丟失滾動的 position。
雖然可以保存 position 並恢復。
您還可以讓您的活動忽略配置更改,以便它不會重新創建。 通過在清單中執行此操作:
<activity
android:name=".main.MainActivity"
android:configChanges="keyboardHidden|orientation|screenSize"
android:launchMode="singleTop">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
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