I want to create a new instance of a Fragment in a PagerAdapter with some method like Fragment1.newInstance(0);
but this does not enter the Fragment onCreateView method, where I want to take its layout... How can I make it enter the lifecycle method?
EDIT: For the swipe tabs I am using an external library, that extends PagerAdapter, maybe thats the problem?
Everything you need is described here. See section "Adding a fragment to an activity" especially to solve your problem.
This is because ViewPager doesn't recreate fragment on each swipe .. it creates fragment only once and keeps in memory and recreate once after it goes offScreenpageLimit() ...For recreating fragment each time you swipe ,you have to set
mViewPager.setOffscreenPageLimit(0);
But this method is not recommended if you have so many pages in viewpager (atleast more than 10)..
in your pager adapter class return the instance like this
#Override
public Fragment getItem(int position){
return Fragment1.newInstance(position);
}
And in your Fragment create a static instance like this
public static NearbyOffersFragment newInstance(int position) {
Fragment1 f = new Fragment1();
Bundle b = new Bundle();
b.putInt("position", position);
f.setArguments(b);
return f;
}
and onCreate of your fragment retrieve the postion
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
position = getArguments().getInt("position");
}
Related
I have a ViewPager which holds Fragments. ViewPager has an adapter of FragmentStatePagerAdapter
Adapter's getItem method.
#Override
public Fragment getItem(int position) {
String text= dbHelper.getText(position);
CustomFragment frg = new CustomFragment(text);
return frg;
}
I am initializing the fragment in the getItem method of the adapter.
Everything works perfectly.
When the orientation changes however, instead of restoring my initialized fragments, CustomFragments are created using the default constructor of CustomFragment. So this creates fragments with dummy data.
What is the reason of this?
How can i restore the previously created fragments?
The ideal way to initialise your Fragments is to create a factory method like:
public static CustomFragment newInstance(String text) {
Bundle arguments = new Bundle();
arguments.put("someText", text);
CustomFragment fragment = new CustomFragment();
fragment.setArguments(arguments);
return fragment;
}
and get the arguments with getArguments() in the onCreate() method and process it to initialise whatever you want in the fragment.
This way when your fragments are recreated on configuration change, the arguments are persisted and the Fragments take care of themselves when their onCreate() method is called.
You might have noticed the lint warnings about the same if you are using the latest tools.
I am having problems with fragments or maybe rather the way I want them to work.
In my activity I have a layout container (R.id.container1) to which I add a fragment (FragMain) programmatically at startup.
In the fragment I have 2 Fragments (Frag1, Frag2) and a ViewPager which loads several other fragments (FragA, FragB, FragC, FragD, FragE) via a FragmentPagerAdapter.
On a button press I replace the whole content of R.id.container1, so FragMain is replaced with another Fragment (FragSub).
Now when I press the back button, FragMain is loaded again, but the ViewPager isn't fully initialized, some Fragments are missing. From what I observed, it's always FragB and FragD missing, If I scroll to the empty views, the app crashes. The other fragments seem to be fine. What's going wrong here?
This thread suggests using getChildFragmentManager in creation of the PagerAdapter, but I am already doing that... Fragment in ViewPager not restored after popBackStack
I am accessing the fragments via e.g.
((FragA)((PagerAdapter)viewPager.getAdapter()).getItem(0));
Is this the best way?
Some Code :
MainActivity's onCreate
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pagerFragList = new Vector<Fragment>();
pagerFragList.add(Fragment.instantiate(this, FragA.class.getName()));
pagerFragList.add(Fragment.instantiate(this, FragB.class.getName()));
pagerFragList.add(Fragment.instantiate(this, FragC.class.getName()));
pagerFragList.add(Fragment.instantiate(this, FragD.class.getName()));
pagerFragList.add(Fragment.instantiate(this, FragE.class.getName()));
FragMain fragMain = (FragMain)getSupportFragmentManager().findFragmentByTag(FragMain.debugTag);
if(fragMain==null) fragMain = new FragMain();
FragmentHelper.replaceSupportFragment(this, fragMain, R.id.container1, false, FragMain);
}
Helper
public Vector<Fragment> getFragList() {
return pagerFragList;
}
FragMain's onViewCreated
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
pagerAdapter = new PagerAdapter(getChildFragmentManager(), ((MainActivity)getActivity()).getFragList());
viewPager = ((ViewPager)view.findViewById(R.id.viewPager));
viewPager.setAdapter(pagerAdapter);
viewPager.setOffscreenPageLimit(5);
viewPager.setCurrentItem(0, true);
}
The PagerAdapter
public class PagerAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments=fragments;
}
#Override
public Fragment getItem(int position) {
return fragments.get(position);
}
#Override
public int getCount() {
return fragments.size();
}
}
Have no idea why this seems to be fixing it on my end, but try commenting out your "viewPager.setOffscreenPageLimit(5);" line.
I'm still investigating and will be back with more if I find anything else useful out.
The other thing it turns out that I had to do was override the "state" methods of a FragmentStatePagerAdapter like this:
#Override
public Parcelable saveState() {
return null;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
//do nothing
}
In order to bypass whatever strange thing that was causing problems (must have had something to do with saving and restoring the states of nested fragments in a ViewPager...
There are alot of permutations involving the state of fragments and backstack transitions. For debug, it may help to isolate the event you are working with (backbutton , orientation change ... ) and to look at the following before and after your event....
state of fragment manager which includes the backstack i believe...
//debug
getFragmentManager().dump("", null,
new PrintWriter(System.out, true), null);
see this thread
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.
I am following the example FragmentTabsPager under the Samples from ActionBarSherlock.
In my case, I have created a simple SherlockActivity with the TabsPager and the same code from the sample for the FragmentPagerAdapter.
I created two fragments (different classes). The first one contains just four buttons. Depending of which one is clicked, the main Activity gets a code (e.g. 1,2,3,4). I get correctly the code for the pressed button.
Now, in the second Fragment I want to draw something depending on that code, or what is the same, update dynamically its view.
I have been searched for a solution but I haven´t got anything. In this case I have this:
[MainActivity.java]
public static class TabsAdapter extends FragmentPagerAdapter
implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final TabHost mTabHost;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
[...]
#Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
I managed to update the Bundle info.args with the new value, but I don´t know how to pass it to the fragment correctly and order it to update its dynamic View.
Is this possible?
Thanks in advance.
UPDATE
Finally, I used what Sunny kindly explained. I kept an SparseArray with my Fragments so I could definitely access them as I know its position inside MainActivity:
[MainActivity.java]
//Once the user presses the button on the first fragment, the callback calls
// this function
public void onImageSelected(int iNumber){
MySecondFragment msf = (MySecondFragment)mTabsAdapter.getFragment(POS_1);
if(msf != null){
msf.setNumImage(iNumber);
msf.updateView();
}
}
And finally in MySecondFragment.java I can access my Layout components (e.g. a GridView), as they were initialized during onCreateView, so I put all the code I needed inside my updateView() method.
For instance, I update the content of a GridView:
[MySecondFragment.java]
myGridView.setBackground(getResources().getDrawable(iCode));
HTH
UPDATE 2
I have included the following code in order to save the fragments into the state bundle of the main activity. When the application changes from portrait to landscape or viceversa (it is recreated) the function getItem is not being called, so the SparseArray map is not refilled again with the necessary Fragments:
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString(CURRENT_TAB, mTabHost.getCurrentTabTag());
getSupportFragmentManager().putFragment(outState, MyFirstFragment.class.getName(), mTabsAdapter.getFragment(POS_1));
getSupportFragmentManager().putFragment(outState, MySecondFragment.class.getName(),
mTabsAdapter.getFragment(POS_2));
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
if (savedInstanceState != null) {
MyFirstFragment mff = (MyFirstFragment) getSupportFragmentManager().getFragment(savedInstanceState, MyFirstFragment.class.getName());
if(mff != null)
mTabsAdapter.setFragment(POS_1, mff);
MySecondFragment msf = (MySecondFragment) getSupportFragmentManager().getFragment(
savedInstanceState, MySecondFragment.class.getName());
if(msf != null)
mTabsAdapter.setFragment(POS_2, msf);
mTabHost.setCurrentTabByTag(savedInstanceState
.getString(CURRENT_TAB));
}
}
Also, inside the TabsAdapter class:
public Fragment getFragment(int pos) {
return map.get(pos);
}
public void setFragment (int position, Fragment fragment) {
map.put(position, fragment);
}
HTH
The source for FragmentPagerAdapter shows that Fragments are given the following tag:
"android:switcher:" + viewId + ":" + id;
Where viewId is the R.id of your ViewPager and id is the page number.
Therefore you can retrieve the second page's Fragment by using:
activity.getSupportFragmentManager().findFragmentByTag(
"android:switcher:" + pager.getId() + ":2")
Where pager is your ViewPager. You'd then want to cast that returned Fragment to whatever specific class you have, then call a method to pass in the information you need.
anhanniballake answer might work. But This might break in future.
To actually get the fragment you can define a sparesArray in your TabAdapter class
private SparseArray<Fragment> map;
and add your fragments in this array
#Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
Fragment fragment = Fragment.instantiate(mContext, info.clss.getName(), info.args);
map.put(position, fragment);
return fragment;
}
You also need to remove the fragment from map when fragment get destroy
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
map.remove(position);
super.destroyItem(container, position, object);
}
Now define a public method in TabAdapter class which can get Fragments
public Fragment getFragment(int pos) {
return map.get(pos);
}
Now in Your Main SherlockFragementActivity you can get the instance of any fragment
MyFragment f = (MyFragment) mTabsAdapter.getFragment(1); // 1 means second fragment from left
Now call any method in your fragments using the fragment instance you got above
f.doAnyThingInMySecondFragment();
doAnyThingInMySecondFragment must be declared public :)
Firstly, I know these subjects have been created a lot of time on stackoverflow, but I don't have found the solution to my problems. Secondly, I'm french, so my english is not perfect, sorry per advance and tell me if you don't understand something. And to finish this introduction, it's the first time that I'm dealing with fragments, so, sorry if there is something that I don't have well understand !
I have three buttons, that allow to switch between three fragments.
Inside one of these fragments, I have a view pager with two fragments. For the moment, each fragments (there are 5), only contains a TextView.
I'm using the latest version of android-support-v4 (I have read a lot of subject in stackoverflow that say that the latest version of support solve the "Recursive entry to executePendingTransactions" error that I have).
My two problems :
When I click two times in one button, I have an IllegaleStateException "can't change tag of fragment". I was able to fix that by creating a new fragment on onButtonSelected method, but I don't want to recreate fragment each time, for memory reasons and for functional reasons : fragment have to keep her state. This problem is not my main problem, indeed, i know that to disable the button when user is already on fragment is possible, but it's strange to have an exception when this management is not done, no ?.
When I go out from the fragment with the view pager, and I go back to this fragment, I have an IllegalStateException "Recursive entry to executePendingTransactions". I can fix this by setting my adapter on an handler, or use FragmentStatePagerAdapter instead of FragmentPageAdapter (see Display fragment viewpager within a fragment), but even if my application don't crash, when I go back to my fragment with the view pager, the view pager has disapear !
Can you help me ?
Java source code is bellow, layout source code is, I think, useless.
MainActivity :
public class MainActivity extends SherlockFragmentActivity{
private SherlockFragment fragmentOne, fragmentTwo, fragmentThree;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// this.fragmentOne = new fragmentOne();
// this.fragmentTwo = new fragmentTwo();
// this.fragmentThree = new fragmentThree();
// Call new or instanciate ? What's the correct way ?
this.fragmentOne = (SherlockFragment) SherlockFragment.instantiate(this, FragmentOne.class.getName());
this.fragmentTwo = (SherlockFragment) SherlockFragment.instantiate(this, FragmentTwo.class.getName());
this.fragmentThree = (SherlockFragment) SherlockFragment.instantiate(this, FragmentThree.class.getName());
// Add fragment
FragmentTransaction transaction = (
this.getSupportFragmentManager().beginTransaction()
);
transaction.add(
R.id.tab_fragment,
this.fragmentOne,
this.fragmentOne.toString()
);
transaction.commit();
}
public void onButtonSelected(View v){
switch (v.getId()){
case R.id.button_one_tab:{
showFragment(this.fragmentThree);
break;
}
case R.id.button_two_tab:{
showFragment(this.fragmentOne);
break;
}
case R.id.button_three_tab:{
showFragment(this.fragmentTwo);
break;
}
default:{
break;
}
}
}
public void showFragment(SherlockFragment fragmentToShow){
FragmentTransaction transaction = (
this.getSupportFragmentManager().beginTransaction()
);
transaction.replace(R.id.tab_fragment, fragmentToShow, fragmentToShow.toString());
transaction.commit();
}
}
Fragment two and three only inflate a layout that only contains a TextView.
Fragment one (note that i'm using a DirectionalViewPager - a lib - instead of a ViewPager):
public class FragmentOne extends SherlockFragment{
private FragmentOneAdapter fragmentOneAdapter;
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Set up the pager
final DirectionalViewPager pager = (DirectionalViewPager)getActivity().findViewById(R.id.pager);
if (this.fragmentOneAdapter== null){
this.fragmentOneAdapter= new FragmentOneAdapter (getActivity().getSupportFragmentManager());
}
pager.setAdapter(fragmentOneAdapter);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_landing_page, container, false);
}
FragmentOneAdapter :
public class FragmentOneAdapter extends FragmentPagerAdapter{
private ArrayList<SherlockFragment> fragmentsList;
public FragmentOneAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
SherlockFragment fragmentFour = new FragmentFour();
SherlockFragment fragmentFive = new FragmentFive();
this.fragmentsList = new ArrayList<SherlockFragment>();
this.fragmentsList.add(fragmentFour);
this.fragmentsList.add(fragmentFive);
}
#Override
public Fragment getItem(int position) {
return this.fragmentsList.get(position);
}
#Override
public int getCount() {
return this.fragmentsList.size();
}
}
Thanks per advance for your help !
I have solved my problem !
I have simply replace getSupportFragmentManager() on FragmentOne to getChildFragmentManager(). Then, I have edited my onButtonSelected's method by creating a new instance of fragment each time instead of using my three different instances (if I don't do that, I have an exception : java.lang.IllegalStateException: Activity has been destroyed).
I have still a problem with this solution : I lose the state of each fragment each time I'm switching between fragmentOne, fragmentTwo and fragmentThree. Do you have a solution for that ?