Originally I had a single fragment loaded in my MainActivityclass. I used the following in
onCreate
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(new TimeTableFragment(), TIMETABLEFRAGMENT_TAG)
.commit();
}
and in
onResume
if(*setting has changed*){
TimeTableFragment tf = (TimeTableFragment) getSupportFragmentManager()
.findFragmentByTag(TIMETABLEFRAGMENT_TAG);
if (null != tf) {
tf.onStudentIdChanged();
}
}
The onStudentIdChanged() method would refresh the fragment data as preference settings have changed.
I have now refactored this activity to use FragmentPagerAdapterand load two different fragments in tabs. Both fragments are instances of the same TimetableFragment class, but with different parameters passed when creating.
FragmentPagerAdapter methods
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a Fragment
switch (position) {
case 1:
case 2:
return TimeTableFragment.newInstance(position);
case 0:
//todo add the single day here
return TimeTableFragment.newInstance(position);
}
return null;
}
TimetableFragment Method
public static TimeTableFragment newInstance(int sectionNumber) {
TimeTableFragment fragment = new TimeTableFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
Now that this is working, in onResume of my MainActivityI am no longer able to access the Fragments using findFragmentByTag, as they are not added in this way during onCreateand I can no longer call the onStudentIdChanged method.
How, for all created instances of the Timetable Fragment can I call this method and have the data updated / refreshed?
In your FragmentPagerAdapter imprementation, add private SparseArray<Fragment> mFragments = new SparseArray<Fragment>();
Modify your getItem method as follows:
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a Fragment
Fragment fragment = null;
switch (position) {
case 1:
case 2:
fragment = mFragments.get(position);
if (fragment == null) {
fragment = TimeTableFragment.newInstance(position);
mFragments.append(position, fragment)
}
break;
case 0:
//todo add the single day here
fragment = mFragments.get(position);
if (fragment == null) {
fragment = TimeTableFragment.newInstance(position);
mFragments.append(position, fragment)
}
break;
}
return fragment;
}
Now when you can get instance of fragment by position.
Related
My current implementation of FragmentStatePagerAdapter creates new fragments every time it is called by viewpager.
I Want to save states of fragments which are previously loaded and wnat to reuse them.
I think to achieve this I have to implement InstantiateItem but not clear how to?
This is my code for FragmentStatePagerAdapter
using System.Collections.Generic;
//using Android.App;
using Android.Views;
using Hollard.MLAM.Android.Fragments.Fna;
using Object = Java.Lang.Object;
using Android.Support.V4.App;
public FnaFragmentPagerAdapter(FragmentManager fm)
: base(fm)
{
_registeredFragments = new Dictionary<int, Fragment>();
}
public override Fragment GetItem(int position)
{
Fragment fragment = null;
switch ((FnaStep)position)
{
case FnaStep.First:
fragment = new FnaStep1Fragment();
break;
case FnaStep.Second:
fragment = new FnaStep2Fragment();
break;
case FnaStep.Third:
fragment = new FnaStep3Fragment();
break;
case FnaStep.Fourth:
fragment = new FnaStep4Fragment();
break;
case FnaStep.Fifth:
fragment = new FnaStep5Fragment();
break;
case FnaStep.Sixth:
fragment = new FnaStep6Fragment();
break;
default:
break;
}
return fragment;
}
public override int Count
{
get { return PageCount; }
}
public Fragment GetRegisteredFragment(ViewGroup container, int position)
{
global::Android.Support.V4.App.Fragment fragment = null;
if (!_registeredFragments.TryGetValue(position, out fragment))
{
InstantiateItem(container, position);
_registeredFragments.TryGetValue(position, out fragment);
}
return fragment;
}
}
public enum FnaStep
{
First = 0,
Second,
Third,
Fourth,
Fifth,
Sixth
}
}
Please help me How to implement FragmentStatePagerAdapter, so it can reuse fragments which are already created.
You should save instances of your fragments and not instantiate them each time. In other words, instead of this line
fragment = new FnaStep1Fragment();
you should use
fragment = _FnaStep1FragmentInstance;
such that _FnaStep1FragmentInstance was initialized in the constructor of the container activity.
I'm currently working with an application that has "swipey-tabs" and uses the following PagerAdapter:
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
return new HomeFragment();
case 1:
return new ListFragment();
case 2:
return new ChartFragment();
}
return null;
}
#Override
public int getCount() {
return 3;
}
}
I'm using the following code to communicate with one of my fragments from the main activity:
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == 1)
{
if (resultCode == Activity.RESULT_OK)
{
String className = data.getExtras().getString("class_name");
if (className.trim().length() > 0) {
HomeFragment homeFrag = (HomeFragment) getSupportFragmentManager().findFragmentById(R.id.home_fragment);
if(homeFrag != null) {
Log.d("MainActivity", "homeFrag is not null");
homeFrag.newClass(className);
}else{
Log.d("MainActivity", "homeFrag is null");
HomeFragment newFragment = new HomeFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.home_fragment, newFragment);
transaction.commit();
newFragment.newClass(className);
}
addSubjectToDataBase(className);
}
}
}
}
My problem is that when I try to communicate with the fragment from the main activity, I seem to get multiple fragments existing at the same time. When I change the orientation of the screen or restart the activity, I get the modified version of the fragment, but when I swipe back and forth to view the fragments, I get the old, non-modified version of the fragment. The fragment manager doesn't seem to be registering the fragments created by the adapter because though I know the fragments have been created, the fragment manager always returns a null home fragment.
How should I go about avoiding this problem, and what is the best way to communicate with the fragment from the main activity?
After reading through this post I worked out a solution to my own question. The problem was that since FragmentPagerAdapter manages its own fragments, the fragment that I was trying to access wasn't the same as the one being used by the view pager.
I worked out a way of accessing the tags of the fragments that are used by the view pager by modifying my modifying my PagerAdapter as such:
public class TabsPagerAdapter extends FragmentPagerAdapter {
protected String homeTag;
protected String listTag;
protected String chartTag;
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
Log.d("Adapter", "returning new homeFragment");
return new HomeFragment();
case 1:
return new ListFragment();
case 2:
return new ChartFragment();
}
return null;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
Fragment createdFragment = (Fragment) super.instantiateItem(container, position);
switch (position){
case 0:
homeTag = createdFragment.getTag();
break;
case 1:
listTag = createdFragment.getTag();
break;
case 2:
chartTag = createdFragment.getTag();
break;
}
return createdFragment;
}
public String getHomeTag(){
return homeTag;
}
public String getListTag(){
return listTag;
}
public String getChartTag(){
return chartTag;
}
#Override
public int getCount() {
return 3;
}
}
Then, it was a simple matter to modify my code to access the correct fragments after I had access the proper fragment tags:
HomeFragment homeFrag = (HomeFragment) getSupportFragmentManager().findFragmentByTag(mAdapter.getHomeTag());
if(homeFrag != null) {
Log.d("MainActivity", "homeFrag is not null");
homeFrag.newClass(className);
}else{
Log.d("MainActivity", "homeFrag is null");
HomeFragment newFragment = new HomeFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.pager, newFragment, madapter.get);
transaction.commit();
newFragment.newClass(className);
It's not elegant but I would do something like this (Maybe someone will post a better solution):
In a singleton, I'll put an array of fragment:
public static Fragment[] sShownFragments = new Fragment[3];
Then in the getItem() method:
if(SingletonClass.sShownFragments[index]!=null){
return mFragments[index];
}
switch (index) {
case 0:
SingletonClass.sShownFragments[index] = new HomeFragment();
break;
case 1:
SingletonClass.sShownFragments[index] = new ListFragment();
case 2:
SingletonClass.sShownFragments[index] = new ChartFragment();
default:
SingletonClass.sShownFragments[index] = new Fragment();
}
return SingletonClass.sShownFragments[index];
Then in the getCount():
return SingletonClass.sShownFragments.length();
Now in your onActivityResult():
\\some code ...
((HomeFragment)SingletonClass.sShownFragments[0]).newClass(className);
\\ some other code...
I have built an Android application that uses tabs to navigate. I am using fragments for the majority of the application, however I need to display one activity. How do i display an activity in case 2. Below is the code i have at the moment, i know it returns a fragment but how do i enable the use of both?
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#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).
System.out.println("current position = " + position);
Fragment fragment = null;
switch(position){
case 0:
return new diaryFragment();
case 1:
return new newEntryFragment();
case 2:
return new Calendarnew();
}
return null;
}
private void displayView(int position) {
// update the main content by replacing fragments
Fragment fragment = null;
switch (position) {
case 0:
fragment = new diaryFragment();
break;
case 1:
fragment = new newEntryFragment();
case 2:
fragment = new Calendarnew();
break;
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, fragment).commit();
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
Hi I dont actually get what you are up to but try reading this, maybe it could somehow solve your issue. https://stackoverflow.com/a/2958586/4470313
The application has a main activity (MainActivity.java) with three tabs (fragments). I can navigate between them using the swipe left (riht) or clicking on a specific tab.
Upon starting the application, the 1st fragment is shown.
If I go to the 2nd fragment from the 1st fragment and then back to the 1st fragment, nothing happens (onResume() of the 1rd fragment isn't called), so it doesn't refresh it's content.
If I go to the 3rd fragment from the 1st fragment and then directly back to the 1st fragment, the onCreateView() of fragment1 is created and it's onResume() is called, which is correct.
If I go from the 3rd fragment to the 2nd fragment, the onCreateView() and onResume() of fragment1 are called, but not the onCreateView of fragment2.
I guess the logic in MainActivity isn't right, so I would kindly ask someone to take a look and tell me what could be wrong.
MainActivity.java:
public class MainActivity extends FragmentActivity implements ActionBar.TabListener {
CollectionPagerAdapter mCollectionPagerAdapter;
public TTSocket socket;
DBHandler db;
public String logged_user;
private LogedinPerson person;
ViewPager mViewPager;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Bundle extras = getIntent().getExtras();
logged_user = extras.getString("logged_user");
socket = TTSocket.getInstance();
socket.currentRef = this;
db = new DBHandler(this);
person=db.getLogedInPerson();
socket.dbHandler=db;
socket.person=person;
if(!socket.isInit){
String typeInitStr = "{\"Type\":\"Init\", \"UserId\":\""+ person.getUserId() +"\"}";
socket.Send(typeInitStr);
}
mCollectionPagerAdapter = new CollectionPagerAdapter(getSupportFragmentManager());
// Set up action bar.
final ActionBar actionBar = getActionBar();
// Specify that we will be displaying tabs in the action bar.
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Set up the ViewPager, attaching the adapter and setting up a listener
// for when the
// user swipes between sections.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mCollectionPagerAdapter);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
Log.d("TEST",position+"");
// the corresponding tab.
// We can also use ActionBar.Tab#select() to do this if
// we have a reference to the Tab
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mCollectionPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter.
// Also specify this Activity object, which implements the
// TabListener interface, as the
// listener for when this tab is selected.
if(i == 0){
actionBar.addTab(actionBar.newTab()
.setIcon(R.drawable.messages)
.setTabListener(this));
}else if(i == 1){
actionBar.addTab(actionBar.newTab()
.setIcon(R.drawable.contacts)
.setTabListener(this));
}else{
actionBar.addTab(actionBar.newTab()
.setIcon(R.drawable.history)
.setTabListener(this));
}
}
}
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
socket.currentRef = this;
socket.dbHandler=db;
socket.person=person;
//mCollectionPagerAdapter.notifyDataSetChanged();
}
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the primary sections of the app.
*/
public class CollectionPagerAdapter extends FragmentPagerAdapter {
final int NUM_ITEMS = 3; // number of tabs
public CollectionPagerAdapter(FragmentManager fm) {
super(fm);
}
/*
#Override
public Fragment getItem(int i) {
Fragment fragment = new TabFragment();
Bundle args = new Bundle();
args.putInt(TabFragment.ARG_OBJECT, i);
fragment.setArguments(args);
return fragment;
}
*/
#Override
public Fragment getItem(int position) {
Fragment fragment = new Fragment();
Bundle args = new Bundle();
args.putInt(TabFragment.ARG_OBJECT, position);
switch (position) {
case 0:
Log.i("Fragment", "0");
fragment = new Tab1Fragment();
fragment.setArguments(args);
return fragment;
case 1:
Log.i("Fragment", "1");
fragment = new Tab2Fragment();
fragment.setArguments(args);
return fragment;
case 2:
Log.i("Fragment", "2");
fragment = new Tab3Fragment();
fragment.setArguments(args);
return fragment;
default:
break;
}
return fragment;
}
#Override
public int getCount() {
return NUM_ITEMS;
}
#Override
public CharSequence getPageTitle(int position) {
String tabLabel = null;
switch (position) {
case 0:
tabLabel = getString(R.string.label1);
break;
case 1:
tabLabel = getString(R.string.label2);
break;
case 2:
tabLabel = getString(R.string.label3);
break;
}
return tabLabel;
}
}
/**
* A fragment that launches other parts of the demo application.
*/
public static class TabFragment extends Fragment {
public static final String ARG_OBJECT = "object";
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Bundle args = getArguments();
int position = args.getInt(ARG_OBJECT);
int tabLayout = 0;
switch (position) {
case 0:
tabLayout = R.layout.tab1;
break;
case 1:
tabLayout = R.layout.tab2;
break;
case 2:
tabLayout = R.layout.tab3;
break;
}
View rootView = inflater.inflate(tabLayout, container, false);
return rootView;
}
}
}
Strange onPause(), onResume() behaviour() in fragments
It's not strange behaviour but native behaviour of ActionSherlock. This kind of behaviour is used for caching -> optimalisation for older devices with lower RAM this is reason why fragments are cached.
If you need to update content of fragment don't try to replace its layout or something similar. If you want to update fragment when scrolling between pages, you need to use method of FragmentPagerAdapter:
#Override
public int getItemPosition(Object object) {
// implementation
return super.getItemPosition(object);
}
This method is called when you will call
notifyDataSetChanged();
on your FragmentPagerAdapter. It's handy method for make updates of your fragments. There are more ways how to do it but here i'll show you how I'm doing it.
Let your fragments implement interface for example called Updateable:
interface Updateable {
public void update();
}
public class MyFragment extends SherlockFragment implements Updateable {
#Override
public void update() {
// perform Fragment updates
}
}
And in this method you will perform updates. Now back to getItemPosition() method. This method will be used for invoking update() method from Fragment i.e:
#Override
public int getItemPosition(Object object) {
Fragment f = (Fragment) object;
// determine which fragment
if (f instanceof MyFragment) {
((MyFragment) f).update(); // invokes update() method
}
return super.getItemPosition(object);
}
Now whenever you scroll page or tap on some tab (you need also call notifyDataSetChanged()) you are able to make Fragment updates. This way is more efficient against destroying and recreating fragment(s) each time you scrolling or clicking on tabs. But how i said this is not only solution there are more possible solutions.
Note: getItemPosition() can return two values: POSITION_NONE and UNCHANGED. Difference between both is that first indicates that Fragment will be always destroyed and recreated that is not very efficient and second indicates that Fragment won't be changed (is in on right place).
For more detailed explanation look here.
That is because ViewPager doesn't hide all fragments you switch.
You can control this behaviour by setOffscreenPageLimit
I have a section my class which is for handling what fragment to load for the FragmentPagerAdapter. Right now it loads fragments just fine but now I want to implement a FragmentActivity and I am having a problem figuring how to create it as I cant use "newinstance" since its type of Activity, and on top of it, I dont know how to call that FragmentActivity as its different from loading just a Fragment via "newinstance" method. My second tab is the one that I would like to be extended to FragmentActivity.
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private Context _context;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
_context= getApplicationContext();
}
#Override
public Fragment getItem(int i) {
Fragment f = new Fragment();
switch(i){
case 0:
f=News.newInstance(_context);
break;
case 1:
f=Info.newInstance(_context);
break;
case 2:
f=Files.newInstance(_context);
break;
case 3:
f=Donate.newInstance(_context);
break;
}
/*
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
fragment.setArguments(args);
*/
return f;
}
#Override
public int getCount() {
return 4;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0: return getString(R.string.title_section1).toUpperCase();
case 1: return getString(R.string.title_section2).toUpperCase();
case 2: return getString(R.string.title_section3).toUpperCase();
case 3: return getString(R.string.title_section4).toUpperCase();
}
return null;
}
}
My guess is that I cant use getitem methods as that for only switching Fragments and that I would have to use something like:
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_content, new BasicFragment());
ft.commit();
Can someone help point me in the right direction?
Can someone help point me in the right direction?
This is not supported. It certainly is not possible with FragmentPagerAdapter, which only works with fragments.