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[英]How to restore fragment state after resume w/o savedInstanceState?
[英]How to restore savedInstanceState of fragment?
我能夠按如下方式保存outState,但是當我第二次登錄此AttendanceFragment.cs時無法還原。
public override void OnSaveInstanceState(Bundle outState)
{
base.OnSaveInstanceState(outState);
dataGotFromServer = JsonConvert.SerializeObject(dataList);
outState.PutString(KEY_OUTSTATE, dataGotFromServer);
}
我在這里嘗試還原但無法獲取
public override void OnViewStateRestored(Bundle savedInstanceState)
{
base.OnViewStateRestored(savedInstanceState);
if(savedInstanceState!=null)
{
var result = savedInstanceState.GetString(KEY_OUTSTATE, dataGotFromServer);
}
}
而且我嘗試了CreateView(),OnActivityCreated()和Create(),但還原失敗。
我的片段替換代碼是
public void ReplaceFragment(Context context, Fragment newFragment, string TAG)
{
Android.Support.V4.App.FragmentManager fragmentManager = ((FragmentActivity)context).SupportFragmentManager;
Android.Support.V4.App.FragmentTransaction ft = fragmentManager.BeginTransaction();
ft.Replace(Resource.Id.HomeFrameLayout, newFragment);
ft.AddToBackStack(TAG);
ft.Commit();
}
編輯:這就是我所說的片段
case (Resource.Id.nav_attendance):
var role = session.GetUserDetails().Get(SessionManagement.KEY_ROLE).ToString();
if (role=="Student")
{
Fragment attendanceTabFragment = new AttendanceTabFragment();
customFragment.ReplaceFragment(this, attendanceTabFragment,typeof(AttendanceTabFragment).Name);
}else
{
Fragment attendanceFragment = new AttendanceFragment();
customFragment.ReplaceFragment(this, attendanceFragment, typeof(AttendanceFragment).Name);
}
任何想法或示例代碼非常感謝。 謝謝。
除非處理包含Fragment的Activity,否則將不會調用Fragment的OnSaveInstanceState
。
在一種情況下,您使用Fragment.Arguments
是一個選項而不是單例/靜態變量來交換片段進出。
回復 : getArguments / setArguments
在使用參數時:
Arguments
OnPause
替代中,使用您需要保存的項目更新Arguments / Bundle。 OnResume
替代中,讀取您需要還原的Arguments / Bundle項目。 片段示例:
public class Fragment1 : Fragment
{
public Fragment1(System.IntPtr javaReference, Android.Runtime.JniHandleOwnership transfer) : base(javaReference, transfer)
{
CreateArgumentBundle();
}
public Fragment1()
{
CreateArgumentBundle();
}
void CreateArgumentBundle()
{
Arguments = new Bundle();
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.Inflate(Resource.Layout.Frag1, container, false);
}
public override void OnPause()
{
base.OnPause();
Arguments.PutString("someKey", "StackOverflow");
}
public override void OnResume()
{
base.OnResume();
var someKeyString = Arguments.GetString("someKey", "someDefaultString(new bundle)");
Log.Debug("SO", someKeyString);
}
}
在您的ReplaceFragment
確保要在Replace
調用中分配TAG
:
public void ReplaceFragment(Context context, Fragment newFragment, string TAG)
{
SupportFragmentManager
.BeginTransaction()
.Replace(Resource.Id.fragmentContainer, newFragment, TAG)
.AddToBackStack(TAG)
.Commit();
}
在調用ReplaceFragment
之前,請在創建新片段之前檢查片段是否存在( FindFragmentByTag
),此示例僅將兩個片段交換進出,如果管理器中不包含兩個片段,則僅創建新片段:
button.Click += delegate
{
toggle = !toggle;
var frag = SupportFragmentManager.FindFragmentByTag(toggle ? "frag1" : "frag2");
frag = frag ?? ( toggle ? (Fragment)new Fragment1() : (Fragment)new Fragment2() );
ReplaceFragment(this, frag, toggle ? "frag1" : "frag2");
};
注意:在回收托管活動的情況下,您仍然需要處理其他Fragment生命周期事件:
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