I am new in view pager.i have 2 pages in view pager..each contain button..i want show button after page fully loaded.Now button is showing half scrolling it self..
class MyPageAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
#Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}
#Override
public int getCount() {
return this.fragments.size();
}
public int getItemPosition(Object object) {
return POSITION_NONE;
}
adding page
pageAdapter = new MyPageAdapter(activity.getSupportFragmentManager(), fragments);
viewpager.setId(position);
viewpager.setAdapter(pageAdapter);
fragment:
public class secondclass extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_secondclass, container, false);
return rootView;
}
please help me..
Just use OnPageChangeListener.
Actually you need to do some tedious tasks for this to be done.
First your activity containing the viewpager should have a way to communicate with the fragments of the viewpager. once you are done with this.
Then set OnPageChangeListener on the viewpager
and one of the overridden callback methods would be the following one
#Override
public void onPageSelected(int position) {
// you know the position now. send the message to the fragment at this position to show the button or do any particular task
}
you are all set to go
In viewpager nearby fragments are loaded even before they are actually visible to the user, this is done so as to provide a smooth scrolling effect.
So onCreateView and onResume methods of the second fragment is already called...even before the user scrolls to the second page.
So to do something exactly when the user loads a page completely we need to user the onPageSelected method and with the help of the position argument we notify the fragment at that position to do the tasks.
In your case show the button...so you need to set visibility of the button INVISIBLE in the layout and make it visible when the page is selected.
For the above thing to work your activity needs to have a reference to the fragment...or you may request the viewpageradapter to provide you the reference by doing a bit caching of the current fragment...apply any logic of yours.
Assume all your fragments are of type MyFragment and have a method doVisibleTask to make the button visible AND getItem of your view pager adapter returns the same instance everytime for a particular position.
you could do the following
#Override
public void onPageSelected(int position) {
// get the reference to the fragment
MyFragment mf = (MyFragment)viewPagerAdapter.getItem(position);
mf.m=doVisibleTask();
// you know the position now. send the message to the fragment at this position to show the button or do any particular task
}
Related
I have several fragments within a viewpager, and the first fragment (TimelineFragment) is being replaced whenever the user chooses to browse a different community.
I'm able to successfully change the TimelineFragment when I changed my FragmentPagerAdapter to FragmentStatePagerAdapter since FragmentPagerAdapter does not update the fragment even when I use pagerAdapter.notifyDataSetChanged()
Hence, I used FragmentStatePagerAdapter with the following code:
#Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
public void setItem(int position, Fragment fragment) {
fragmentList.set(position, fragment);
}
#Override
public int getCount() {
return fragmentList.size();
}
#Override
public int getItemPosition(Object object) {
return PagerAdapter.POSITION_NONE;
}
The problem is whenever I move to a fragment, that fragment is being refreshed. Which makes my recyclerview within each fragment reload all lists and go to the top of that list.
My goal here is that when the user has chosen to view a different community, the timeline fragment (ALONE, hopefully exluding other fragments) will be the only fragment to reload, and load the respective list based on the chosen community.
the method onCreateView in fragment calls each time you move between 3 fragments in view pager. so the solution is:
1- add static boolean loaded=false; in your fragment
2- before calling the code that refreshes the recyclerview or any code you don't want to call add
if(!loaded){
//your code
...
loaded=true;
}
I am reusing the same fragment to display an image with an animation. The problem which I facing is the fragment view is loaded with the animation before it is visible to the user while swiping. Below is my PagerAdapter
public class PollsAdapter extends FragmentStatePagerAdapter {
/** Constructor of the class */
int clickPosition = 0;
ArrayList<Polls> pollsList = new ArrayList<Polls>();
public PollsAdapter(FragmentManager fm,ArrayList<Polls> pollsList) {
super(fm);
this.pollsList=pollsList;
}
/** This method will be invoked when a page is requested to create */
#Override
public Fragment getItem(int arg0) {
PollsFragment myFragment = new PollsFragment();
Bundle data = new Bundle();
data.putSerializable("poll", pollsList.get(arg0));
data.putInt("position", arg0);
myFragment.setArguments(data);
return myFragment;
}
/** Returns the number of pages */
#Override
public int getCount() {
return pollsList.size();
}
public int getItemPosition(Object item) {
return POSITION_NONE;
}
}
This is how I set my viewPager
pollsAdapter = new PollsAdapter(fm, pollsList);
viewPager = (ViewPager) _rootView.findViewById(R.id.pager);
viewPager.setAdapter(pollsAdapter);
I tried by using `viewPager.setOffscreenPageLimit(1); but this didn't work. I'm sure I miss something. Please help me to solve this problem.
This is --unfortunately-- not possible. To display the flip animation, ViewPager has to pre-load at least the fragments to the left/right of the currently displayed fragment.
Because of this, the minimum possible value for ViewPager.setOffscreenPageLimit() is 1 as at least the direct neighbours need to be available.
In your case, the problem is rather that your fragment seems to be starting an animation as soon at is created.
In that case, you will need to change the starting logic for your animation. Your fragment can get notified by the ViewPager as soon as it is scrolled to (see ViewPager.OnPageChangeListener) for the mechanism). Note that the OnPageListener is not called when your activity is resumed so you also need to handle this case..
How to determine when Fragment becomes visible in ViewPager has more information on that topic.
I have a FragmentPagerAdapter for a viewPager Which initially has only one Fragment in it. I want to dynamically add a new Fragment to the adapter when user swipes from right to left, and dynamically remove a Fragment when user swipes from left to right.I have tried to use this library https://github.com/commonsguy/cwac-pager but in that library we have an option to add and remove fragments on button clicks. I have tried to add a OnPageChangeListener to the viewpager but the callback methods ( onPageScrolled and onPageScrollStateChanged) are being called more than once which results in addition of more than one fragment to the FragmentPagerAdapter. So please shed some light on how to do this.
#dora: i think in your case FragmentStatePagerAdapter will help you. I have mentioned its use below as per my understanding.I hope it will help you in taking decision.
There are two ways to implement ViewPager:
• FragmentStatePagerAdapter
• FragmentPagerAdapter
FragmentStatePagerAdapter class consumes less memory, because it destroys fragments, as soon as they are not visible to user, keeping only saved state of that fragment
FragmentPagerAdapter: when there are less number of fragments. But using AndroidFragmentPagerAdapter for large number of fragments would result choppy and laggy UX.
Number of page hold by a viewPager?
The number of items that any ViewPager will keep hold of is set by the setOffscreenPageLimit() method. The default value for the offscreen page limit is 3. This means ViewPager will track the currently visible page, one to the left, and one to the right. The number of tracked pages is always centered around the currently visible page.
Please follow this link for code: http://www.truiton.com/2013/05/android-fragmentpageradapter-example/
I know this post is old, but I struggled to figure this out so I'll answer it anyway.
You want to use FragmentStatePagerAdapter and override getItemPosition(). Create a list of stuff you want to pass down to the fragment, call notifyDataSetChanged(), and you're all set!
Here's the adapter:
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
List<String> mKeyList = new ArrayList<>();
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(mKeyList.get(position));
}
#Override
public int getCount() {
return mKeyList.size();
}
#Override
public CharSequence getPageTitle(int position) {
return "SCOUT " + (getCount() - position);
}
public void add(int position, String key) {
mKeyList.add(position, key);
notifyDataSetChanged();
}
}
And here's the fragment:
public static class PlaceholderFragment extends Fragment {
private static final String ARG_SCOUT_KEY = "scout_key";
public static PlaceholderFragment newInstance(String key) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putString(ARG_SCOUT_KEY, key);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.current_scout_fragment, container, false);
//getArguments().getString(ARG_SCOUT_KEY));
return rootView;
}
}
I want to dynamically add a new Fragment to the adapter when user swipes from right to left, and remove dynamically remove a Fragment when user swipes from left to right.
AFAIK, that will not be supported by any PagerAdadpter. It certainly will not be supported by ArrayPagerAdapter. The page needs to exist, otherwise you cannot swipe to it. You cannot swipe first, then add the page later.
Moreover, I have never found a use case for your proposed pattern that could not be handled by having the page be in the adapter, but not populating the page (i.e., whatever the expensive work is that you appear to be trying to avoid) until the swipe begins.
Need some help with my problem of updating pages while using viewpager. I am using a simple viewpager with FragmentStatePagerAdapter. All I want to do is get access to the current fragment/view so as I can update some textviews in my fragment/view. I searched around in the forum and came to know few things
- One of the ways to handle this is by setting tag in instantiateItem() call back of the adapter and retreive the view by findViewbyTag. I could not understand how to implement this and I am also not sure if that will work for FragmentStatePagerAdapter.
- I explored other options as suggested in various forums, but cannot make them work.
My code is very much same as in a android http://developer.android.com/training/animation/screen-slide.html. Basic components are the same (Fragment activity xml with some display components including a textview, viewpager xml with just a view pager in it, a Fragment class and the main FragmentActivity class). in my FragmentActivity class I have added a pageChangelistener to my viewpager so as I can do my textview changes during onPageSelected().
Any help is is appreciated.
Adding the code for reference.
Public class myActivity extends FragmentActivity
//Variable declarations
protected void onCreate(Bundle savedInstanceState) {
ViewPager mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
View CurrView;
OnPageChangeListener pageChangelistener = new OnPageChangeListener() {
#Override
public void onPageSelected(int pageSelected) {
doTextViewChnges();//access the text view and update it based on pageSelected
---THIS IS WHERE I AM STUCK IN TRYING TO GET THE TEXTVIEW IN MY CURRENT FRAGMWNT/VIEW-------
}
mPager.setOnPageChangeListener(pageChangelistener);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(android.support.v4.app.FragmentManager fm) {
super(fm);
}
#Override
public android.support.v4.app.Fragment getItem(int position) {
return ScreenSlidePageFragment.create(position, <other parameters I want to pass>);
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
in your OnPageChangeListener:
OnPageChangeListener pageChangelistener = new OnPageChangeListener() {
#Override
public void onPageSelected(int pageSelected) {
ScreenSlidePageFragment currentFragment = (ScreenSlidePageFragment) mPagerAdapter.getItem(pageSelected)
doTextViewChnges();//access the text view and update it based on pageSelected
---THIS IS WHERE I AM STUCK IN TRYING TO GET THE TEXTVIEW IN MY CURRENT FRAGMWNT/VIEW-------
}
i assume you want to access your fragments from your activity and update the views.Fragments are parts of activities and their views can be accessed by them. Fragments are created dynamically in viewadapters and there is no straight forward and easy way to Tag them. You may simply access a fragment by its index number.first one is 0 second one is 1 and so on...
//access your fragment(in your case your first fragment)
//this part should be inside your doTextViewChnges()
Fragment fragment = (Fragment ) adapterViewPager
.getFragment(0);
if (fragment != null) {
//call a public method inside your fragment to update your text view
fragment .updateYourTextView();
}
Edit: inside your fragment create the following method and update your textview from there.
void updateYourTextView() {
yourTextView.setText("yourtext");
}
I am having a hard time figuring out the next thing.
What I have: I have a viewpager and several pages in it. In this question only two of them is important, lets call them Fragment1 and Fragment2 and they are next to each other. Fragment1 contains a listview which is filled with data from the internet (external database). Fragment2 contains a simple button.
My goal: If I click on the button in Fragment2, I add a new item to the external database. I would like to update/refresh the listview in the Fragment1 with this new item.
The notifyDataChanged() doesnt work in my case, however so far I was convinced that it reinstantiates every pages.. I am going to introduce my problem the clearest way I can, so lets see the code I have, this is my ViewPager adapter:
class MyPagerAdapter extends FragmentStatePagerAdapter {
public List<String> fragmentsA;
public MyPagerAdapter(FragmentManager fm) {
super(fm);
fragmentsA = fragments;
}
#Override
public Fragment getItem(int position) {
return Fragment.instantiate(context, fragmentsA.get(position));
}
#Override
public CharSequence getPageTitle(int position) {
return mEntries.get(position % CONTENT.length).toUpperCase();
}
#Override
public int getCount() {
return mEntries.size();
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
}
Fragment1 onCreateView() (shortly):
public View onCreateView(LayoutInflater inflater, final ViewGroup container,
Bundle savedInstanceState) {
getData();
View view = inflater.inflate(R.layout.latestapps_tab, container, false);
lw = (ListView) view.findViewById(R.id.lw);
context = getActivity().getApplicationContext();
act = this.getActivity();
m_adapter = new ItemAdapter();
lw.setAdapter(m_adapter);
return view;
}
I create the ViewPager and the adapter, I set the adapter for the ViewPager afterwards I fill the my viewpager with my fragments in my Main class. After this I am goint to have a fully functional ViewPager with 2 fragments.
pager = (ViewPager)findViewById( R.id.viewpager );
adapter = new MyPagerAdapter(getSupportFragmentManager());
indicator = (TabPageIndicator)findViewById( R.id.indicator );
pager.setAdapter( adapter );
indicator.setViewPager( pager );
pager.setCurrentItem(INITIAL_PAGE);
pager.setOffscreenPageLimit(3);
//adding fragments to the pager
fragments.add( Fragment1.class.getName());
fragments.add( Fragment2.class.getName());
In the Fragment1 I have a listview with some textviews in every list item. The loading works perfectly: I create the ArrayLists and I fill thoes lists with data from the external database. After loading is done, I fill the listviews with these tons of data.
In Fragment 2 I click on the button and I would like that listview to be updated so a new row should be created in the listview with some data from the external database. (of course writing into the database works)
My guess, that I might not refresh the ArrayLists or I dont reinstantiate the Fragment1, so the getDataFromSQL() method never turns only if I exit and launch the application again or I swipe so much in the ViewPager that the Fragment1 gets detached. So I cannot update or refresh the Fragment1. Could someone help in this questionL?
EDIT
I managed to make it happen with delivering a message to the fragment2 to update itself. But I am not sure if it is a good solution and there is not a better way, i.e. just refreshing somehow the whole fragment.
SOLUTION
Okay I think it must have been my laziness but I solved it now. For everyone who still wants to refresh a fragment from another one or just make conection between fragments, I tell you the appropriate approach:
You have to implement your own listener which helps you communicate between the fragments through the holder activity. This can be found here: http://developer.android.com/training/basics/fragments/communicating.html . Very simple and useful.
You have to retrieve the fragment, which is again simple: Retrieve a Fragment from a ViewPager These Q offers several acceptable way, I used the SpareArray solution.
Thank you for the help anyway!
you need be able to get your fragments from your activity, to do that you need to get the fragment from your adapter, you will need to add a couple methods to your page adapter
public Fragment getFragment(ViewPager container, int position, FragmentManager fm) {
String name = makeFragmentName(container.getId(), position);
return fm.findFragmentByTag(name);
}
private String makeFragmentName(int viewId, int index) {
return "android:switcher:" + viewId + ":" + index;
}
then from your activity make the following method
public Fragment getFragmentbyPosition(int position) {
return adapter.getFragment(pager, position, getSupportFragmentManager());
}
now on fragment2 call the following:
Fragment1 fragment1 = (Fragment1) ((MyActivity)getActivity()).getFragmentbyPosition(0);
now you will be able to call public methods on fragment1 from fragment 2, so just use that in your onClick and tell fragment1 to update it's listview.
now the reason makeFragmentName works is that is how the FragmentPagerAdapter creates the tag for the fragments it makes.