On state loss or screen rotation and when my boolean flag is true, I want to recreate my screen. However, the fragment manager still has the previous fragment attached and it gets loaded.
What can I do to get rid of that fragment?
public class ViewPagerAdapter extends FragmentPagerAdapter {
private String[] mData;
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
mData= new String[0];
}
#Override
public Fragment getItem(int position) {
Bundle bundle = new Bundle();
bundle.putInt("key", position);
Fragment fragment = new MyFragment();
fragment.setArguments(bundle);
return fragment;
}
#Override
public int getCount() {
return mData.length;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
return mData[position];
}
public void setData(String[] data) {
mData= data;
}
}
Piece of code in Activity onCreate()
mViewPagerAdapter = new ViewPagerAdapter(getFragmentManager());
mViewPagerAdapter.setData(data);
viewPager.setAdapter(mViewPagerAdapter);
You may override instantiateItem() to detect screen rotation like a Fragment can.
Code example:
#Override
public boolean isViewFromObject(View view, Object o) {
return o == view;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
View view = getActivity().getLayoutInflater().inflate(R.layout.pager_item,
container, false);
return view;
}
Note: instantiateItem() occurs upon screen rotation. Activity does not detect that. The hint is that the class does not have onCreateView() like the fragment class.
Related
I have a ViewPager.When some data changed,i set the adapter for the ViewPager again by call ViewPager.setAdapter(new Adapter).What i wonder is,the Fragment is re-create (it jump on onDestroyView and then onCreateView) and my Edittext cannot set again the text.And if i remove all Fragment from FragmentTransaction and then setAdapter,the Fragment create a new one -> my Edittext set the text well.So is Fragment recreate itselft NOT from UI thread? ( Because i try the edditext.post and my edditext from first scenario work).Here is the code
Adapter:
public class PagerAdapter extends FragmentPagerAdapter {
private final ArrayList<Fragment> fmAct;
public PagerAdapter(FragmentManager supportFragmentManager, ArrayList<Fragment> fm) {
super(supportFragmentManager);
fmAct = fm;
}
#Override
public Fragment getItem(int position) {
return fmAct.get(position);
}
#Override
public int getCount() {
return fmAct.size();
}
#Override
public int getItemPosition(#NonNull Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
return ((PrFragment) getItem(position)).getFragmentName();
}
what i do when re-set the adapter
fm.clear();
fragmentAttendanceCome = new FragmentAttendanceCome();
fragmentAttendanceCome.setFragmentName(getString(R.string.title_attendance));
fragmentAttendanceCome.setParentActivity(this);
fragmentAssessment = new FragmentAssessment();
fragmentAssessment.setFragmentName(getString(R.string.daily_evaluation));
fragmentAssessment.setParentActivity(this);
fragmentInfo = new FragmentInfo();
fragmentInfo.setParentActivity(this);
fragmentInfo.setFragmentName(getString(R.string.title_infomation));
fm.add(fragmentAttendanceCome);
fm.add(fragmentAssessment);
fm.add(fragmentInfo);
viewPager.setAdapter(new PagerAdapter(getSupportFragmentManager(), fm));
This is my fragment :
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
textview.setText(data)
// i already Bind it but i lazy to copy it,everything work well
}
Here's the inner class that contains fragments and changes fragment views on swipe. This class is defined in an Activity.
private class ViewPagerAdapter extends FragmentPagerAdapter {
private int count;
ViewPagerAdapter(FragmentManager fm, int count) {
super(fm);
this.count = count;
}
#Override
public Fragment getItem(int position) {
switch(position) {
case 0:
return new FriendsListFragment();
case 1:
Bundle bundle = new Bundle();
bundle.putString(Keys.TAG, ChatListFragment.class.getSimpleName());
ChatListFragment chatListFragment = new ChatListFragment();
chatListFragment.setArguments(bundle);
return chatListFragment;
case 2:
return new MoreFragment();
default:
return null;
}
}
#Override
public int getCount() {
return count;
}
}
Here I would like to add a code that sets tags to each fragment, so that I can recognize which fragment I'm at.
I searched quite much, and I haven't found a proper answer for this question, so please help.
You can override the setPrimaryItem method of your FragmentPagerAdapter.
private class ViewPagerAdapter extends FragmentPagerAdapter {
protected int currentPosition = -1;
protected Fragment currentFragment;
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// ....
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
super.setPrimaryItem(container, position, object);
this.currentPosition = position;
if (object instanceof Fragment) {
this.currentFragment = (Fragment) object;
}
}
public int getCurrentPosition() {
return currentPosition;
}
public Fragment getCurrentFragment() {
return currentFragment;
}
}
Just use getCurrentPosition or getCurrentFragment methods to get information about current Fragment.
I came across a strange issue in my project.
I have implemented infinite viewpager adapter using FragmentStatePagerAdapter
Code for same is:
public class DashBoardAdapter extends FragmentStatePagerAdapter {
ArrayList<AbstractFragment> fragments;
private int MAXFRAGMENTS=0;
public DashBoardAdapter(FragmentManager fm, ArrayList<AbstractFragment> fragments) {
super(fm);
this.fragments = fragments;
MAXFRAGMENTS=fragments.size();
}
#Override
public AbstractFragment getItem(int position) {
return fragments.get(position%MAXFRAGMENTS);
}
#Override
public int getCount() {
return Integer.MAX_VALUE;
}
#Override
public CharSequence getPageTitle(int position) {
return fragments.get(position%MAXFRAGMENTS).getTitle();
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
int virtualPosition = position % MAXFRAGMENTS;
return super.instantiateItem(container, virtualPosition);
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
int virtualPosition = position % MAXFRAGMENTS;
super.destroyItem(container, virtualPosition, object);
}
#Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
MAXFRAGMENTS = fragments.size();
}
}
And the Main Activitycode(Function only) is something like this:
public void initializeViewPager()
{
verticalViewPager = (VerticalViewPager) findViewById(R.id.verticalviewpager);
enabledPages=new ArrayList<>();
enabledPages.addAll(getEnabledPages(false));
adapter=new DashBoardAdapter(getSupportFragmentManager(),enabledPages);
verticalViewPager.setAdapter(adapter);
verticalViewPager.setPageTransformer(true, new PageTransformer());
verticalViewPager.setCurrentItem(999+position);
verticalViewPager.setOffscreenPageLimit(1);
verticalViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if(adapter!=null)
title.setText(adapter.getPageTitle(position));
}
#Override
public void onPageSelected(int position) {
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
}
private ArrayList<AbstractFragment> getEnabledPages(boolean a)
{
ArrayList<AbstractFragment> fragments=new ArrayList<>();
fragments.add(FragmentAttendance.newInstance(fragments.size()));
fragments.add(FragmentCompensation.newInstance(fragments.size()));
if(a)
fragments.add(FragmentTimeOff.newInstance(fragments.size()));
if(a)
fragments.add(FragmentCalendar.newInstance(fragments.size()));
if(a)
fragments.add(FragmentPeople.newInstance(fragments.size()));
if(a)
fragments.add(FragmentProvisions.newInstance(fragments.size()));
position = fragments.size()-(999+position)%fragments.size();
return fragments;
}
Layout of activity contains just a Viewpager.
And the Fragments, I have used is just copy of below fragment with different names
public class FragmentAttendance extends AbstractFragment {
public static final String ARG_SECTION_NUMBER = "section_number";
String title ="Testing";
public static FragmentAttendance newInstance(int sectionNumber) {
FragmentAttendance fragment = new FragmentAttendance();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public FragmentAttendance() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.card_attendance, container, false);
return rootView;
}
#Override
public String getTitle() {
return title;
}
}
Layout of fragment has just LinearLayout with a TextView.
The code is running superb if I am adding fragments more than three fragments. Howsoever as soon as the number of added fragments gets below four. My code Works in strange behavior.
Some of errors are Fragment already initialised
Other are Forward scrolling shows fragement View Howsoever when I scroll backward No view appears.
The working code can be tested by passing true to getEnabledPages(true);
And the non working code can be tested by passing false to getEnabledPages(false);
Please someone help me in this strange behaviour.
I want to update container fragment base on data inside the page fragment in ViewPager. I used this solution Retrieve a Fragment from a ViewPager and it works fine when I swipe the view.
But I cannot figure out how to get hint (callback) if first page is loaded. At the beginning? Of course onPageSelected is called but when I try to get fragment I got null.
Data data = null;
mViewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener(){
#Override
public void onPageSelected(int position) {
PageFragment page = MyPagerAdapter.getPageFragment(position);
if(page != null)
data = page.getData();
else
Log.w(TAG,"page is null"); //i get it at first time. :(
}
});
Below MyPageAdapter which I use (accordint to Retrieve a Fragment from a ViewPager)
public class MyPagerAdapter extends FragmentStatePagerAdapter {
SparseArray<PageFragment> registeredFragments = new SparseArray<PageFragment>();
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return ...;
}
#Override
public Fragment getItem(int position) {
return PageFragment.newInstance(...);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment fragment = (Fragment) super.instantiateItem(container, position);
registeredFragments.put(position, fragment);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
registeredFragments.remove(position);
super.destroyItem(container, position, object);
}
public PageFragment getPageFragment(int position) {
return registeredFragments.get(position);
}
}
I'm working with viewpager inside fragments. I'm using pagerAdapter to switch between two pages via XML. Here is the code:
public class DemoPagerAdapter extends FragmentPagerAdapter {
public DemoPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
Fragment f;
switch (index) {
case 0:
f = new FirstFragment();
break;
case 1:
f = new SecondFragment();
break;
}
return f;
}
#Override
public int getCount() {
return 2;
}
}
And I'm calling it like this:
public class DemoFragment1 extends Fragment {
private ViewPager viewPager;
private DemoPagerAdapter mAdapter;
public DemoFragment1() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.security, container, false);
mAdapter = new DemoPagerAdapter(getActivity().getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
showPages(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
return rootView;
}
Everything works fine. But if I move to DemoFragment2 and then come back to DemoFragment1, PagerAdapter is not called.
Your ViewPager is nested in a Fragment, you should use the ChildFragmentManager, modify:
mAdapter = new DemoPagerAdapter(getChildFragmentManager());
I also assume the ViewPager will keep the off screen fragment in memory, thus it might not call getItem(int index) again. Add
viewPager.setOffscreenPageLimit(0);
return rootView;
Well, I encontered this issue last week.
When I put the ViewPager in the fragment with a FragmentPagerAdapter, after I move forward to anoter Fragment and back, the pager' s view not exists.
I supposed is the FragmentPagerAdapter won' t retain its view in the ViewPager ' s host Fragment, Their life cycle is not the same. Though you put the VewPager' s host Fragment in the back stack, but the FragmentPagerAdapter' s fragment not. And Then, I gave up FragmentPagerAdapter and tried android.support.v4.view.PagerAdapter, (note, it wont' t use fragment to inject view!), everything is fine!
below is the sample:
private final PagerAdapter coverPager = new PagerAdapter() {
private LayoutInflater mLayoutInflater;
#Override
public int getCount() {
return 2;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
if (mLayoutInflater == null) {
mLayoutInflater = LayoutInflater.from(getActivity());
}
switch (position) {
case 0:
View frontPage = mLayoutInflater.inflate(R.layout.profile_cover, container, false);
ImageView avatar = (ImageView) frontPage.findViewById(R.id.avatar);
Picasso.with(getActivity())
.load(mAvatarUrl)
.placeholder(R.drawable.error)
.error(R.drawable.error)
.into(avatar);
TextView screenName = (TextView) frontPage.findViewById(R.id.screen_name);
screenName.setText("#" + mScreenName);
TextView remark = (TextView) frontPage.findViewById(R.id.remark);
remark.setText(TextUtils.isEmpty(mRemark) ? mScreenName : mRemark);
if (mVerified) {
frontPage.findViewById(R.id.verified).setVisibility(View.VISIBLE);
}
container.addView(frontPage);
return frontPage;
case 1:
View introPage = mLayoutInflater.inflate(R.layout.profile_intro, container, false);
CatnutUtils.setText(introPage, R.id.description, TextUtils.isEmpty(mDescription)
? getString(R.string.no_description) : mDescription);
CatnutUtils.setText(introPage, R.id.location, mLocation);
CatnutUtils.setText(introPage, R.id.profile_url, Constants.WEIBO_DOMAIN + mProfileUrl);
container.addView(introPage);
return introPage;
default:
return null;
}
}
};
and then in your onViewCreate or OnCreateView, put mViewPager.setAdapter(coverPager);
the instantiateItem is the place to put the page' s view, similar like the FragmentPagerAdapter!
It' s just like put the FragmentAdapter' s view int the ViewPager' s host Fragment, not the other fragment!
Hope it' s helpful!