Develop Reference

ViewPage Fragment disappear when reload again

The following is layout
test.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="Click"
android:id="#+id/button"
/>
<!-- Framelayout to display Fragments -->
<FrameLayout
android:id="#+id/frame_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
test_detail.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Hello"
android:id="#+id/textView" android:layout_gravity="center_horizontal"/>
</LinearLayout>
common_view_pager_layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="#+id/MainViewerPage"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<android.support.v4.view.PagerTabStrip
android:id="#+id/TitlePageTabStrip"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.v4.view.ViewPager>
</LinearLayout>
The following is my Activity code
public class TestFragmentActivity extends FragmentActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.test);
Button button = (Button) this.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, new HomeFragment()).commit();
}
});
}
public class HomeFragment extends Fragment {
private PagerAdapter _adapter;
public HomeFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.common_view_pager_layout, container, false);
this._adapter = new PagerAdapter(TestFragmentActivity.this);
this._adapter.add(new DetailFragment());
ViewPager pager = (ViewPager) view.findViewById(R.id.MainViewerPage);
pager.setAdapter(this._adapter);
return view;
}
}
public class DetailFragment extends Fragment {
public DetailFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.test_detail, container, false);
return rootView;
}
}
public class PagerAdapter extends FragmentPagerAdapter {
private ArrayList<Fragment> _fragments;
public PagerAdapter(FragmentActivity activity) {
super(activity.getSupportFragmentManager());
this._fragments = new ArrayList<Fragment>();
}
public void add(Fragment fragment) {
this._fragments.add(fragment);
}
#Override
public Fragment getItem(int position) {
return this._fragments.get(position);
}
#Override
public CharSequence getPageTitle(int position) {
return "Test";
}
#Override
public int getCount() {
return 1;
}
}
}
When I click a button the fragment in ViewPager was display
But when I click the button again the fragment disappear
Please help me.

try using this:
in the constructor of your adapter change this :
public class MyPagerAdapter extends FragmentPagerAdapter {
private ArrayList<Fragment> _fragments;
public MyPagerAdapter(FragmentManager activity) {
super(activity);
this._fragments = new ArrayList<Fragment>();
}
public void add(Fragment fragment) {
this._fragments.add(fragment);
}
#Override
public Fragment getItem(int position) {
return this._fragments.get(position);
}
#Override
public CharSequence getPageTitle(int position) {
return "Test";
}
#Override
public int getCount() {
return 1;
}
}
and when you want to create the adapter send getChildFragmentManager() to its constructor
public class HomeFragment extends Fragment {
private MyPagerAdapter _adapter;
public HomeFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.common_view_pager_layout, container, false);
ViewPager pager = (ViewPager) view.findViewById(R.id.MainViewerPage);
this._adapter = new MyPagerAdapter(getChildFragmentManager());
this._adapter.add(new DetailFragment());
pager.setAdapter(this._adapter);
return view;
}
}
I test it and it works, any problem comment it.
Good Luck!

In your Fragment class, in the onCreate() method, you have to call setRetainInstance(true) like this:
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
This tells the FragmentManager to keep your fragments on reloads.
In addition, check your manifest file doesn't have any
android:screenOrientation
config changes where you are basically saying you will handle reloads due to config changes yourself.

In PagerFragment 's onResume() add this:
#Override
public void onResume() {
super.onResume();
for (Fragment fragment : getFragmentManager().getFragments()) {
if (fragment instanceof Tab1Fragment || fragment instanceof Tab2Fragment) {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.detach(fragment);
ft.attach(fragment);
ft.commit();
}
}
}

Try to add this lines in your code:
public int getItemPosition(Object object) {
return POSITION_NONE;
}
and Add the below lines
pager.setOnPageChangeListener(new OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
... anything you may need to do to handle pager state ...
adapter.notifyDataSetChanged(); //this line will force all pages to be loaded fresh when changing between fragments
}
Under
pager.setAdapter(adapter);
Hope this may help you!

Ensure you pass the adapter instance the child fragment manager, not the fragment manager.
Like this:
this._adapter = new PagerAdapter(getChildFragmentManager());

move from a fragment to another in an activity

From what I understand from this thread, fragments can be easily replaced with another.
However in my case, I have 2 fragments combined in scrollable Activity, so when I say "move", I mean going from the fragment left to the right or right to the left without replacing any fragment with another. Is this somehow possible?

you could use ViewPager for that. And on your adapter class you will have to switch between the fragments via getItem(). Eclipse/new AndroidProject/ swipe with/out tabs. And check the example code generated by Android.
edit:
create xml file call it main_activity.xml
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Main" >
<android.support.v4.view.PagerTitleStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="#FAFAFA"
android:paddingBottom="4dp"
android:paddingTop="4dp"
android:textColor="#36466E" />
create a class call it Main
public class Main extends FragmentActivity {
SectionsPagerAdapter mSectionsPagerAdapter;
ViewPager mViewPager;
Context ctx;
static MySQLiteHelper db;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
mSectionsPagerAdapter.notifyDataSetChanged();
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch(position){
case 0:
fragment = new GridApp();
break;
case 1:
fragment = new ListApp();
break;
}
return fragment;
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Select App";
case 1:
return "Selected Apps";
}
return null;
}
}
}
now create a class called GridApp and ListApp
GridApp class.
public class GridApp extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.gridpp,
container, false);
}
}
ListApp class
public class GridApp extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.listapp,
container, false);
}
}
and you are done.

recreate view of fragment via button

I've got a FragmentActivity which show the correct fragment, using a ViewPager. I added a Fragment StatePagerAdapter to the ViewPager. If I push a button at a Fragment, it should be recreated (onCreateView should be called again). The fragments are articles and if the user is offline, I'll show him "please check your networkconnection" and a button to reload. The button called a method in the FragmentActivity, but I don't know how implement it. Maybe I can destroy and recreate the current Fragment?
here the important part of the FragmentActivity:
private ArrayList<Fragment> fragments;
protected void onCreate(Bundle savedInstanceState)
{
context = this;
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_article_page_slider);
...
pages = datahandler.getCount(...);
viewPager = (ViewPager) findViewById(R.id.articlePager);
PagerAdapter pagerAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
viewPager.setAdapter(pagerAdapter);
viewPager.setCurrentItem(startPosition);
fragments = new ArrayList<Fragment>(pages);
}
public void reloadData(View v)
{
// TODO
((ArticlePageFragment)fragments.get(viewPager.getCurrentItem())).refresh();
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter
{
public ScreenSlidePagerAdapter(FragmentManager fm)
{
super(fm);
}
#Override
public Fragment getItem(int position)
{
Fragment fragment = new ArticlePageFragment();
Bundle args = new Bundle();
...
fragment.setArguments(args);
fragments.add(position, fragment);
return fragment;
}
public int getCount()
{
return pages;
}
}
and the Fragment itself:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
activity = getActivity();
ViewGroup rootView = (ViewGroup) inflater.inflate(
R.layout.fragment_article_page, container, false);
CacheDataHandler cdh = new CacheDataHandler(activity);
cdh.open();
String htmlData = cdh.loadData();
rootView.findViewById(R.id.btn_reload_article_data).setVisibility(View.GONE);
webView = ((WebView) rootView.findViewById(R.id.articleFragment));
refresh();
...
return rootView;
}
public void refresh()
{
...
if (htmlData == null)
{
rootView.findViewById(R.id.btn_reload_article_data).setVisibility(View.VISIBLE);
webView.loadData(defaultdata,"text/html", "UTF-8");
}
else
{
webView.loadData(htmlData,"text/html", "UTF-8");
}
}
and the fragment_article_page.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<WebView
android:id="#+id/articleFragment"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<Button
android:id="#+id/btn_reload_article_data"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:onClick="reloadData"
android:text="#string/btn_txt_reload_data"
android:visibility="gone" />
</RelativeLayout>
EDIT
added a private ArrayList<Fragment> fragments in FragmentActivity and transfer the code for manipulating the view in an extra refreshMethod, look ahead. All works fine, if I only click on the first or second Fragment (index 0 and 1). Otherwise I get an IndexOutOfBoundsException. How to initialize and fill the ArrayList?

ViewPager not showing anything

Please, advice. I can't get ViewPager working. Here is what I'am doing:
1) This is my LinearLayout in which I will put the ViewPager. I'am sure that it's work. I can put any View in it:
<LinearLayout
android:id="#+id/view_contact_values_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/view_contact_sub_nav"
android:orientation="vertical"
android:paddingLeft="10dip" >
</LinearLayout>
2) Next I'm creating the ViewPager in code:
private void createViewPager() {
ViewPager viewPager = new ViewPager(this);
DatesPagerAdapter datesPagerAdapter = new DatesPagerAdapter(this);
viewPager.setAdapter(datesPagerAdapter);
viewPager.setCurrentItem(1);
llContainer.addView(viewPager);
}
3) And the ViewPagerAdapter (PagerAdapter):
#Override
public Object instantiateItem(ViewGroup container, int position) {
LayoutInflater inflater = (LayoutInflater) container.getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflater.inflate(R.layout.dates_carusel_item, null);
((ViewPager) container).addView(v, 0);
return v;
}
#Override
public int getCount(){
return 5;
}
But when I open my Activity, there is nothing showing in my LinearLayout.
P.S.: Sorry for the bad question styling. Code tag in this editor is strange.

Take a class extending Fragemnt
class ExampleFragment extends Fragment
{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.dates_carusel_item, null);
return v;
}
And in your PagerAdapter do this
private class DatesPagerAdapter extends FragmentPagerAdapter
{
public DatesPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int arg0) {
ExampleFragment fragment=new ExampleFragment();
Bundle bundle=new Bunlde();
//put bundle data here
fragment.setArguments(bundle);
return fragment;
}
#Override
public int getCount() {
5;
}
}
Whatever view you want to set do it on the Example Fragment and add your viewPager
ViewPager pager=new ViewPager(this);
pager.setAdapter(new DatesPagerAdapter);
llContainer.addView(pager)
Add your ViewPager in xml itself to get it proprly alligned or else you can setLayoutParams in runtime if its a visibilty error
android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" android:layout_below="#id/view_contact_sub_nav"android:id="+id/view_contact_values_container"
android:paddingLeft="10dip">
<android.support.v4.view.ViewPager
android:id="#+id/imagesgallery"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>

ViewPager with FragmentPagerAdapter does not show content

I'm trying to use the Fragment, ViewPager & co. from the Android support library v4. Fragments seem to scroll when I listen to page change events from the pager but the content is not visible. What I basically have is:
A FragmentActivity:
public class MyActivity extends FragmentActivity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
FragmentPagerAdapter fpa = new MyPagerAdapter(this, createFragments());
ViewPager vp = (ViewPager) findViewById(R.id.pager);
vp.setAdapter(fpa);
}
private List<Fragment> createFragments() {
List<Fragment> list = new ArrayList<Fragment>();
list.add(Fragment.instantiate(this, First.class.getName()));
list.add(Fragment.instantiate(this, Second.class.getName()));
list.add(Fragment.instantiate(this, Third.class.getName()));
return list;
}
#Override
protected void onSaveInstanceState(Bundle outState) {
}
A FragmentPagerAdapter:
public class MyPagerAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public MyPagerAdapter(FragmentActivity activity, List<Fragment> fragments) {
super(activity.getSupportFragmentManager());
this.fragments = fragments;
}
#Override
public Fragment getItem(int i) {
return fragments.get(i);
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public boolean isViewFromObject(View view, Object o) {
return view.equals(o);
}
}
And three Fragments that look like this:
public class First extends Fragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.first, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
}
And they have layout like these:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:text="First Fragment"
android:id="#+id/firstText"/>
</LinearLayout>
I originally forgot to add the main layout, here it comes:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_width="fill_parent"/>
</LinearLayout>
I would appreciate if someone can tell me what I am doing wrong.

This is because you have overridden isViewFromObject in MyPagerAdapter.
FragmentPagerAdapter handles isViewFromObject, so you shouldnt override it.
As with me, I reckon most visitors to this post started with a basic PagerAdapter, then realised they needed to page fragments and changed their base class without realising the consequences. Unfortunate, but I couldn't criticise the Android team for this.

Ya correct as Ian Newson told, just remove isViewFromObject overrided method from your code
#Override
public boolean isViewFromObject(View view, Object object) {
return false;
}