First of all I would like to thank the stackoverflow community. Thanks to you I solved so much problems! Usually I bang my head over the wall for hours and I find the solution here (98% percent of the time). This time I would like to share my problem.
This is the first app I'm developing. I have one activity (is this bad?). My app structure is the following: Nav drawer which contains four items - two viewpagers and two static fragments. The viewpagers contains lists with data and if you click on one of the items from the list you are present with a detail page which again is a viewpager. When you are on the detail page you can click and advance to other fragment. The problem is that when I advance to the other fragment onSavedInstance is not called for the viewpagerdetails and I can't retain the fragment state. onSavedInstance will be called if I pass to the FragmentPagerAdapter getFragmentManager(), instead of getChildFragmentManager(), but if I do this when I navigate back, the viewpager items are blank. I have tried using FragmentStatePagerAdapter, but when I click back from the 'other fragment' to return to viewpager details the app crashes with the following error: Fragment no longer exists for key f0: index 0. I have looked over the internet, but I didn't found a working solution. Some say that the problem is from the adapter, but I tried this solution and it didn't work. Also I want to manually retain my fragment state, please don't offer me the fix with the configchanges in the app manifest. I have tried to call onSavedInstanceState from the onStop method, but when I return to the fragment the saved state is empty. Should I implement this with a static variable in my mainActivity?
FragmentPagerAdapter:
public class DetailsSlideAdapter extends FragmentPagerAdapter {
private String[] navMenuTitles;
private FragmentManager manager;
private FragmentTransaction mCurTransaction = null;
private Resources res;
public DetailsSlideAdapter(FragmentManager fm, Resources res) {
super(fm);
this.manager = fm;
navMenuTitles = res.getStringArray(R.array.detailTabs);
this.res = res;
}
#Override
public int getCount() {
return 3;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
DetailsInfo info = new DetailsInfo();
return info;
case 1:
DetailsCast cast = new DetailsCast();
return cast;
case 2:
DetailsOverview overview = new DetailsOverview();
return overview;
default:
return null;
}
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return navMenuTitles[0];
case 1:
return navMenuTitles[1];
case 2:
return navMenuTitles[2];
default:
return navMenuTitles[1];
}
}
Viewpager details:
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Get the ViewPager and set it's PagerAdapter so that it can display items
DetailsSlideAdapter = new DetailsSlideAdapter(getChildFragmentManager(), getResources());
mViewPager = (ViewPager) rootView.findViewById(R.id.DetailsPager);
mViewPager.setOffscreenPageLimit(3);
mViewPager.setAdapter(DetailsSlideAdapter);
// Give the SlidingTabLayout the ViewPager, this must be done AFTER the ViewPager has had
// it's PagerAdapter set.
mSlidingTabLayout = (DetailsSlidingTabLayout) rootView.findViewById(R.id.sliding_tabs);
mSlidingTabLayout.setViewPager(mViewPager);
mSlidingTabLayout.setSelectedIndicatorColors(getResources().getColor(R.color.tabSelected));
}
If other code is needed I will post it. Thanks.
EDIT using FragmentStateAdapter:
App crashes: Fragment no longer exists for key f0: index 0. On the internet people say that the problem is from the adapter, but I tried this solution and it didn't work. Code:
public class DetailsSlideAdapter extends FragmentStatePagerAdapter {
private String[] navMenuTitles;
private FragmentManager manager;
private FragmentTransaction mCurTransaction = null;
private Resources res;
SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
public DetailsSlideAdapter(FragmentManager fm, Resources res) {
super(fm);
this.manager = fm;
navMenuTitles = res.getStringArray(R.array.detailTabs);
this.res = res;
}
#Override
public int getCount() {
return 3;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
DetailsInfo info = new DetailsInfo();
return info;
case 1:
DetailsCast cast = new DetailsCast();
return cast;
case 2:
DetailsOverview overview = new DetailsOverview();
return overview;
default:
return null;
}
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return navMenuTitles[0];
case 1:
return navMenuTitles[1];
case 2:
return navMenuTitles[2];
default:
return navMenuTitles[1];
}
}
#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 Fragment getRegisteredFragment(int position) {
return registeredFragments.get(position);
}
Have you seen this? FragmentStatePagerAdapter
From the Docs:
Implementation of PagerAdapter that uses a Fragment to manage each
page. This class also handles saving and restoring of fragment's
state.
Related
I get the next error: java.lang.IllegalStateException: Fragment already added.
This is a layout getting inflated each time I change tab, as seen in this photo:
![FirstTab]http://prntscr.com/h4e8pc
![SecondTab]http://prntscr.com/h4ebyn
So i get the idea of the problem, but I've tried many ways to fix it with no result. I've tried to use .replace instead of .add, that way it doesnt crash but the map is not loaded. And also tried to delete the fragment as soon as I switch to that tab but the result is similar to the .replace one.
case R.id.navigation_dashboard:
frame = (FrameLayout) findViewById(R.id.content);
frame.removeAllViewsInLayout();
LayoutInflater.from(getApplicationContext())
.inflate(R.layout.activity_prueba_dashboard, frame, true);
fragmentTransaction =
getFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.content2, mMapFragment);
fragmentTransaction.commit();
mMapFragment.getMapAsync(my_maps_class);
I believe it's much cleaner to use viewpager in that situation. Check this code :
public class HomeViewPagerAdapter extends FragmentPagerAdapter {
public static final int FRAGMENT_A_INDEX = 0;
public static final int FRAGMENT_B_INDEX = 1;
public static final int FRAGMENT_C_INDEX = 2;
public static final int FRAGMENTS_COUNT = 3;
public HomeViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case FRAGMENT_A_INDEX:
return FragmentA.newInstance();
case FRAGMENT_B_INDEX:
return FragmentB.newInstance();
case FRAGMENT_C_INDEX:
return FragmentC.newInstance();
default:
return null;
}
}
#Override
public int getCount() {
return FRAGMENTS_COUNT;
}
}
and then link the adapter with the ViewPager in the hosting appcompat activity as here :
HomeViewPagerAdapter homeTabsAdapter = new HomeViewPagerAdapter(getSupportFragmentManager());
homeTabsViewPager.setAdapter(homeTabsAdapter);
and you can easily switch between fragments by calling :
homeTabsViewPager.setCurrentItem(HomeViewPagerAdapter.FRAGMENT_A_INDEX, false);
You seen to be trying replacing the content of the same Fragment, in this case you dont need the FragmentTransaction.
The solution is to create a second fragment on which you have the map, in this case the Transaction is needed.
my SlidingTabLayout restarts my fragment dashboard activity when switching from fragment tags to fragment dashboard, or position 4 to 0.
Here is the code that I have written so far, can anyone shed some light on the situation ?
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
//2 steps creating a fragment, create the fragment class and create the UI for it
Fragment fragment = null;
//we dont want it to return our place holder Fragment instead we want to switch bewtween 3
//create a switch case based on the position applied or the fragment selected
switch (position) {
case HOME:
fragment = Dashboard.newInstance("","");
break;
case TAGS:
fragment = Tags.newInstance("","");
break;
case MY_RECENT:
fragment = MyPosts.newInstance("","");
break;
case TOP:
fragment = Top.newInstance("", "");
break;
}
return fragment;
}
#Override
public int getCount() {
// Show 3 total pages.
return 4;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Home";
case 1:
return "Top";
case 2:
return "Recent";
case 3:
return "Tags";
}
return null;
}
}
You have to load all fragment in one time, you should call this method
int size=4;
viewPager.setOffscreenPageLimit(size);
after set adapter, size is the no of fragment which you want to load first time
I'm developing an app and currently I am trying to add ScreenSlide to it. I managed to do this using a tutorial, but usual sliding between x pages is not quite what I'm looking for.
With code provided below I can slide between 5 pages, but pages aligned in a straight line and you can't go from first page straight to 5th and vise versa.
In my app I have 4 pages. When I slide left I switch between first 2 pages, when I slide right I switch between 2 last pages. On image below you can see how my current code switches page and under it - my goal.
public class MainActivity extends FragmentActivity {
private static final int NUM_PAGES = 5;
private ViewPager mPager;
private ScreenSlidePageFragment[] pages = new ScreenSlidePageFragment[NUM_PAGES];
private PagerAdapter mPagerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_screen_slide);
mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
mPager.setAdapter(mPagerAdapter);
}
#Override
public void onBackPressed() {
if (mPager.getCurrentItem() == 0) {
super.onBackPressed();
} else {
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
}
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return NUM_PAGES;
}
#Override
public Fragment getItem(int position) {
boolean moveRight = mPager.getCurrentItem() < position;
boolean moveLeft = mPager.getCurrentItem() > position;
switch(position){
case 5:
if(moveRight){
return geLog.w("i"
+ "Info", Integer.toString(position));
//return getPageByPosition(2);
if(moveLeft)
return getPageByPosition(2);
}
return new ScreenSlidePageFragment();
}
private Fragment getPageByPosition(int position){
int index = position - 1;
if(index < 0 || index > NUM_PAGES-1)
throw new InvalidParameterException("requested position is invalid");
if(pages[index] == null)
pages[index] = new ScreenSlidePageFragment();
return pages[index];
}
}
}
[UPDATE]
I've managed to write a code that allows me to infinitely slide to the right between 6 different pages. Left side is limited though - I can slide only to the first page(so if I'm on 1st page after I cycled 3 times to the right, I can make only 3 cycles backwards). I think I am very close to finding the solution. Any ideas?
MainActivity.java
public class MainActivity extends FragmentActivity {
private static final int NUM_PAGES = 6;
private ViewPager pager;
private PagerAdapter pagerAdapter;
private List<ScreenSlidePageFragment> slideList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
slideList = new ArrayList<ScreenSlidePageFragment>();
for (int i = 0; i<NUM_PAGES; i++){
ScreenSlidePageFragment slide = new ScreenSlidePageFragment();
slide.setIndex(i+1);
slideList.add(slide);
}
pager = (ViewPager) findViewById(R.id.pager);
pagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
pager.setAdapter(pagerAdapter);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
int _pos = position % NUM_PAGES;
return slideList.get(_pos);
}
#Override
public int getCount() {
return Integer.MAX_VALUE;
}
}
}
ScreenSlidePageFragment.java
public class ScreenSlidePageFragment extends Fragment {
private int index;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
ViewGroup root = (ViewGroup)inflater.inflate(R.layout.slide, container, false);
TextView tw = (TextView) root.findViewById(R.id.textView);
tw.setText(Integer.toString(index));
return root;
}
public void setIndex(int index){
this.index = index;
}
}
One possible workaround is not using viewpager, but creating your own custom Slider, I ended up with this solution, since ViewPager is very unflexible, like for example if you try to do something like Facebook Page app kind of thing.
Cons: you have to manage all the touches and lifecycle.
Another simpler solution for this is basically use the following API if I understand the question correctly it should be enough.
ViewPager.setCurrentItem
This is what I would do.
Since you have a finite amount of screens, I would make an array to save each instance of the ScreenSlidePageFragment you make under a corresponding index. So you can get an instance from that array by using "position". This will allow you to leverage getItem function to do something like
...
private ScreenSlidePageFragment[] pages = new ScreenSlidePageFragment[NUM_PAGES];
...
#Override
public Fragment getItem(int position) {
boolean moveRight = mPager.getCurrentItem() < position;
switch(position){
case 1:
if(moveRight)
return getPageByPosition(3);
return getPageByPosition(2);
case 2:
if(moveRight)
//case when you are in a position 3 and swipe right - return first screen
return getPageByPosition(3);
//if you're swiping left from position 1, return the next screen
return getPageByPosition(1);
case 3:
//write out the rest of your logic
...
}
}
private Fragment getPageByPosition(int position){
int index = position - 1;
if(index < 0 || index > NUM_PAGES-1)
throw new InvalidParameterException("requested position is invalid")
if(pages[index] == null)
pages[index] = new ScreenSlidePageFragment();
return pages[index];
}
Note: code not tested
Basically, you will need to write out the logic to return an existing instance of a fragment based on where you are currently and which position is requested.
You can try ViewPager.setCurrentItem
If you want to navigate to page
viewPager.setCurrentItem(PAGE_POS);
If you want to navigate to page without smooth scroll
viewPager.setCurrentItem(PAGE_POS,false);
I think it's possible to do.
1. Set ViewPager's item count to Integer.MAX_VALUE and current item to Integer.MAX_VALUE/2. It gives you ability to create fake infinite scroll.
2. Realize your logic depending on fragment on current position. It is easy if you store them in your adapter:
#Override
public Fragment getItem(int position) {
ItemFragmentRoot fragment = new ItemFragmentRoot();
mFragmentMap.put(position, fragment);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
mFragmentMap.remove(position);
}
public ItemFragmentRoot getItem(int position){
return mFragmentMap.get(position);
}
And the most difficult part, I think. Since ViewPager cache at least 1 view each side and you don't know which way user going to scroll the only one way is to manualy initialize and reinitialize appearing fragment according to scroll side. Use nested fragment inside each ItemFragmentRoot I mentioned before. All depends on how heavy your view hierarchy.
I can write more code later, if you need.
I'd like to be able to not allow switching to one of my 3 fragments in my custom FragmentPagerAdapter when certain conditions are met. Unfortunately I failed to find any help.
I'd prefer to not remove and re-add the fragment (item 0), as this criterium can change inside the FragmentActivity any time and I'd need the fragment to be able to receive and handle messages.
Any suggestions? Please ask if something's unclear.
Edit: Sharing some code
Main activity:
#Override
protected void onResume() {
super.onResume();
...
_sectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager(), this, cardnumber, pin);
_viewPager = (ViewPager) findViewById(R.id.pager);
_viewPager.setAdapter(_sectionsPagerAdapter);
_viewPager.setOnPageChangeListener(_sectionsPagerAdapter);
_viewPager.setCurrentItem(1);
_viewPager.setOffscreenPageLimit(2);
This seems a bit rude, but it works
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
Bundle args = new Bundle();
switch (position) {
case CUSTOMER_DETAILS_PAGE:
// fragment = _fragments.get(TRLIST_PAGE);
fragment = new UserDetailFragment();
args.putString("TAG", "details");
break;
case BALANCE_PAGE:
// fragment = _fragments.get(BALANCE_PAGE);
fragment = new BalanceFragment();
args.putString("TAG", "balance");
break;
case TRLIST_PAGE:
// fragment = _fragments.get(TRLIST_PAGE);
fragment = new TrListFragment();
args.putString("TAG", "trlist");
break;
default:
break;
}
_listeners.put(position, (MyTabSelectedListener) fragment);
// fragment = (Fragment) _listeners.get(position);
args.putString("cardnumber", _cardnumber);
args.putString("pin", _pin);
fragment.setArguments(args);
return fragment;
}
I want to limit access to the CUSTOMER_DETAILS_PAGE when it would be empty anyway.
After reading corsair992-s answer here https://stackoverflow.com/a/23967701/3153792 and looking at the CWAC-Pager source code here https://github.com/commonsguy/cwac-pager I managed to find what I was looking for.
The key was to change the getItemPosition function (which I didn't even use before) to get the TAG argument (set in getItem) from the fragments and identify them that way:
#Override
public int getItemPosition(Object item) {
Fragment fragment = (Fragment) item;
String title = fragment.getArguments().getString("TAG");
int position = tabs.indexOf(title);
if (position >= 0) {
return position;
} else {
return POSITION_NONE;
}
First I define tags for each tab and a list to hold them in order of appearance:
public static final String CUSTOMER_DETAILS_PAGE = "detail";
public static final String BALANCE_PAGE = "balance";
public static final String TRLIST_PAGE = "trlist";
List<String> tabs = new ArrayList<String>();
Afterwards, I add them in the constructor in the original order:
tabs.add(CUSTOMER_DETAILS_PAGE);
tabs.add(BALANCE_PAGE);
tabs.add(TRLIST_PAGE);
When I need to hide a tab, I just remove it from the list and notify the adapter:
public void disableUserDetail() {
tabs.remove(tabs.indexOf(CUSTOMER_DETAILS_PAGE));
notifyDataSetChanged();
}
My fragment specifically goes to the left side (the beginning) but it would be easy to change:
public void enableUserDetail() {
tabs.add(0, CUSTOMER_DETAILS_PAGE);
notifyDataSetChanged();
}
I had to change getItem and getPageTitle to use the tabs list and TAG constants as identifier (which I also include as arguments for getItemPosition):
#Override
public Fragment getItem(int position) {
String id = tabs.get(position);
Fragment fragment = null;
Bundle args = new Bundle();
if (id.equals(CUSTOMER_DETAILS_PAGE)) {
fragment = new UserDetailFragment();
args.putString("TAG", CUSTOMER_DETAILS_PAGE);
...
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
String id = tabs.get(position);
if (id.equals(CUSTOMER_DETAILS_PAGE)) {
return _ctx.getString(R.string.title_section1).toUpperCase(l);
...
I have this weird issue with the viewPager. When I swipe from one fragment to the next and then swipe back, the layout is correct, but when pressing an element (Listview item for example), the previous java code still did not update with the view. I don't know if I can explain this any better, as it works when I play with the swipe until the fragment works like its supposed to. here is my code:
Main.Java:
public class Main extends FragmentActivity {
SectionsPagerAdapter mAdapter;
ViewPager mViewPager;
// for alert transitions
AlertDialog dialog;
// share button
private ShareActionProvider mShareActionProvider;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// set up button
getActionBar().setDisplayHomeAsUpEnabled(true);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mAdapter);
mViewPager.setPageTransformer(true, new DepthPageTransformer());
}
#Override
public void onBackPressed() {
if (mViewPager.getCurrentItem() == 0) {
// If the user is currently looking at the first step, allow the system to handle the
// Back button. This calls finish() on this activity and pops the back stack.
super.onBackPressed();
} else {
// Otherwise, select the previous step.
mViewPager.setCurrentItem(mViewPager.getCurrentItem() - 1);
}
}
}
SectionsPagerAdapter.java:
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position){
case 0:
return new Important();
case 1:
return new Propositions();
case 2:
return new Information();
}
return null;
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return ("Important Dates").toUpperCase(l);
case 1:
return ("Props").toUpperCase(l);
case 2:
return ("Information").toUpperCase(l);
}
return null;
}
}
The Fragments all use the onCreateView() method.
Thanks in advance for your help!
Maybe a late response, but I've experienced the same issue.
The problem was the DepthPageTransformer you are using from the Android Developers example for PageTransformer.
There is a bug with stacking fragments and layer priority, I assume. By fixing the custom PageTransformer will fix your "swipe back" issue. Or if you don't mind the animation, just remove your custom PageTransformer and use the default animation (by adding nothing).