我制作了一个recyclerview网格,一旦用户按下按钮,它就会填充来自api的数据。旋转屏幕后,短暂恢复滚动位置,然后再滚动回到网格顶部。我正在使用https://medium.com/androiddevelopers/restore-recyclerview-scroll-position-a8fbdc9a9334保留滚动位置:
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)
}
}
我也尝试保存布局状态RecyclerView store / restore state between activities
我的清单条目是:
<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>
屏幕旋转是一次配置更改,它导致活动重新创建,因此您失去了滚动位置。
尽管您可以保存位置并恢复。
您还可以使您的活动忽略配置更改,以使它不会重新创建。通过在清单中执行此操作:
<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>