如何让我保留意见及其状态的片段? [英] How do I let views keep their states in a Fragment?
问题描述
视图(在这种情况下, ViewPager
S)有自己的执行保存和恢复状态,我是依靠它来保持我的ViewPager在同一页上后,设备旋转。
它的工作完全正常的时候ViewPager在一个活动。我会滚动到页面,旋转设备,它还是会成为该网页上。在的onSaveInstanceState
是不需要code。
因为我已经转换该活动成为一个片段。现在,ViewPager不保留其状态!如果我滚动到一个页面,旋转装置,它可以追溯到第1页。
我知道我可以保存和的onSaveInstanceState
和 onCreateView
,但我宁愿让恢复页面认为这样做对自己,尤其是当我添加更多的意见,并就变得更加复杂。
我如何找回这种观点的恢复功能与片段?
下面是我的片段:
进口android.os.Bundle;
进口android.support.v4.app.Fragment;
进口android.support.v4.app.FragmentManager;
进口android.support.v4.app.FragmentStatePagerAdapter;
进口android.support.v4.view.ViewPager;
进口android.support.v7.app.ActionBarActivity;
进口android.support.v7.widget.Toolbar;
进口android.view.LayoutInflater;
进口android.view.View;
进口android.view.ViewGroup;公共类仪表板延伸片段{ 私人PagerAdapter pagerAdapter; @覆盖
公共无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState); pagerAdapter =新PagerAdapter(getChildFragmentManager());
} @覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,捆绑savedInstanceState){
查看查看= inflater.inflate(R.layout.dashboard,集装箱,FALSE); //无关位删除 ViewPager寻呼机=(ViewPager)view.findViewById(R.id.dashboard_pager);
pager.setOffscreenPageLimit(3);
pager.setAdapter(pagerAdapter); PagerSlidingTabStrip标签=(PagerSlidingTabStrip)view.findViewById(R.id.dashboard_tabs);
tabs.setShouldExpand(真);
tabs.setViewPager(寻呼机); 返回视图。
} 类PagerAdapter扩展FragmentStatePagerAdapter实现PagerSlidingTabStrip.CustomTabProvider { 公共PagerAdapter(FragmentManager FM){
超(FM);
} @覆盖
公共片段的getItem(INT位置){
开关(位置){
情况下0:
返回Fragment.instantiate(getActivity(),Fragment1.class.getName());
情况1:
返回Fragment.instantiate(getActivity(),Fragment2.class.getName());
案例2:
返回Fragment.instantiate(getActivity(),Fragment3.class.getName());
} 返回null;
} @覆盖
公众诠释的getCount(){
返回3;
} @覆盖
公共CharSequence的getPageTitle(INT位置){
开关(位置){
情况下0:
返回*删除*;
情况1:
返回*删除*;
案例2:
返回*删除*;
} 返回null;
} @覆盖
公共查看getCustomTabView(ViewGroup中ViewGroup中,int i)以{
返回getActivity()getLayoutInflater()膨胀(R.layout.tab,ViewGroup中,FALSE)。;
}
}
}
href=\"http://stackoverflow.com/a/9646622/609782\">你检查这个答案
如果您发现您的片段仍然活在 onSavedInstanceState()
,你能避免它。
除此之外,我认为你是知道的的android:configChanges =方向|屏幕尺寸
Views (in this case, ViewPager
s) have their own implementation of saving and restoring state, and I was relying on it to keep my ViewPager on the same page after a device rotate.
It worked perfectly fine when the ViewPager was in an Activity. I'd scroll to a page, rotate the device, and it'd still be on that page. No code was needed in onSaveInstanceState
.
I've since converted that Activity into a fragment. Now, the ViewPager doesn't keep its state! If I scroll to a page and rotate the device, it goes back to page 1.
I know that I can save and restore the page in onSaveInstanceState
and onCreateView
, but I'd rather let the view do it on its own, especially as I add more views and it becomes more complex.
How do I get back this view restoring functionality with fragments?
Here's my fragment:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class Dashboard extends Fragment {
private PagerAdapter pagerAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
pagerAdapter = new PagerAdapter(getChildFragmentManager());
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.dashboard, container, false);
// irrelevant bits removed
ViewPager pager = (ViewPager) view.findViewById(R.id.dashboard_pager);
pager.setOffscreenPageLimit(3);
pager.setAdapter(pagerAdapter);
PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) view.findViewById(R.id.dashboard_tabs);
tabs.setShouldExpand(true);
tabs.setViewPager(pager);
return view;
}
class PagerAdapter extends FragmentStatePagerAdapter implements PagerSlidingTabStrip.CustomTabProvider {
public PagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return Fragment.instantiate(getActivity(), Fragment1.class.getName());
case 1:
return Fragment.instantiate(getActivity(), Fragment2.class.getName());
case 2:
return Fragment.instantiate(getActivity(), Fragment3.class.getName());
}
return null;
}
@Override
public int getCount() {
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "*removed*";
case 1:
return "*removed*";
case 2:
return "*removed*";
}
return null;
}
@Override
public View getCustomTabView(ViewGroup viewGroup, int i) {
return getActivity().getLayoutInflater().inflate(R.layout.tab, viewGroup, false);
}
}
}
If you find if your fragment is still alive in onSavedInstanceState()
, you can avoid it.
Apart from that I assume you are aware of android:configChanges= "orientation|screenSize"
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