I am new to android. I have a sliding tab layout and a viewpager with a fragment. I have setup a basic link between these to switch tabs for a count of 5(i.e 5 tabs) The problem is that, in each of these tabs, I want to populate a listview using simplecursoradapter, for which I need the position of each fragment so that I could populate it accordingly. I have got the position in the fragment adapter class, but I am unable to pass it to the main activity. Also, How can I access DBadapter inside my fragment class to populate listview from the database? or is there some other way to do this? Below is my code. Any help is greatly appreciated. Thanks in advance.
public class myFragment extends Fragment{
private ListView mainList;
public static myFragment getInstance(int position){
myFragment MyFragment = new myFragment();
Bundle args = new Bundle();
args.putInt("position", position);
MyFragment.setArguments(args);
return MyFragment;
}
#Override
public View onCreateView(LayoutInflater inflater,
#Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
View layout = inflater.inflate(R.layout.fragment_main_list,container, false);
mainList = (ListView)layout.findViewById(R.id.mainListView);
Bundle bundle = getArguments();
if(bundle!=null){
if(bundle.getInt("position")==0){
mainList.setBackgroundColor(getResources().getColor(R.color.primary500));
}
else if(bundle.getInt("position")==1){
mainList.setBackgroundColor(getResources().getColor(R.color.primary100));
}
else if(bundle.getInt("position")==2){
mainList.setBackgroundColor(getResources().getColor(R.color.primary700));
}
else if(bundle.getInt("position")==3){
mainList.setBackgroundColor(getResources().getColor(R.color.accent));
}
else if(bundle.getInt("position")==4){
mainList.setBackgroundColor(getResources().getColor(R.color.black));
}
}
return layout;
}
}
The Main Activity is as follows:
public class MainActivity extends ActionBarActivity {
private Toolbar toolbar;
private ViewPager mPage;
private SlidingTabLayout mTabs;
DBadapter myDb;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
openDB();
toolbar = (Toolbar)findViewById(R.id.app_bar);
mPage = (ViewPager)findViewById(R.id.pager);
mTabs = (SlidingTabLayout)findViewById(R.id.tabs);
mFab = (FloatingActionButton)findViewById(R.id.fab);
setSupportActionBar(toolbar);
mPage.setAdapter(new myPagerAdapter(getSupportFragmentManager()));
mTabs.setViewPager(mPage);
}
public class myPagerAdapter extends FragmentPagerAdapter{
String[] tabs;
public myPagerAdapter(FragmentManager fm) {
super(fm);
tabs = getResources().getStringArray(R.array.tabs);
}
#Override
public Fragment getItem(int position) {
myFragment MyFragment = myFragment.getInstance(position);
return MyFragment;
}
#Override
public CharSequence getPageTitle(int position) {
return tabs[position];
}
#Override
public int getCount() {
return 5;
}
}
Use this method :
mPage.setOnPageChangeListener(new SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int pos) {
// pos is the position of fragment that app showing
});
UPDATE
in your view pager adapter :
public Fragment getItem(int position) {
return new myFragment(position);
}
And in your fragment class :
public class myFragment extends Fragment{
private int pos
public void myFragment(int position){
this.pos = position;
}
// other code of your class
Related
I have one activity HomeActivity and I have HomePageFragment which have some categories with icon and title of data, when I click on any category I'm sending the clicked item Title name with bundle and opening MultipleFragment and I'm getting clicked title name from the previous fragment, on this multiple fragments I have viewpager inside it..
1) PostFragment,
2) TextFragment
now here's my main question that I want to send clicked item title name to PostFragment and TextFragment,
HomeFragment
public void onItemClick(int position) {
MultiplePost multiplePost = new MultiplePost();
Bundle args = new Bundle();
Categories categoriesClicked = categoriesList.get(position);
args.putString(Title, categoriesClicked.getTitle());
args.putString(ImageUrl, categoriesClicked.getIcon());
multiplePost.setArguments(args);
getActivity().getSupportFragmentManager().beginTransaction()
.replace(R.id.main_frame,multiplePost)
.addToBackStack(null)
.commit();
}
MultiplePost
public class MultiplePost extends Fragment {
private TabLayout tabLayout;
private ViewPager viewPager;
private ViewPageAdapter viewPageAdapter;
private View view;
private FragmentManager mFragmentManager;
public static String title ;
public MultiplePost() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_multiple_post, container, false);
title = getArguments().getString("title");
tabLayout = view.findViewById(R.id.tablayout_id);
viewPager = view.findViewById(R.id.viewPager_id);
viewPageAdapter = new ViewPageAdapter(getChildFragmentManager());
viewPageAdapter.AddFragment(new PostFragment(), "");
viewPageAdapter.AddFragment(new TextFragment(), "");
viewPager.setAdapter(viewPageAdapter);
tabLayout.setupWithViewPager(viewPager);
tabLayout.getTabAt(0).setIcon(R.drawable.photo);
tabLayout.getTabAt(1).setIcon(R.drawable.file);
PostFragment post = new PostFragment();
Bundle args = new Bundle();
args.putString("title", title);
post.setArguments(args);
getActivity().getSupportFragmentManager().beginTransaction();
.replace(R.id.main_frame, post)
.commit();// and this's changing whole fragment with PostFragment and
//so i can't see my viewpager on MultiplePost
return view;
}
}
ViewPagerAdapter
public class ViewPageAdapter extends FragmentPagerAdapter {
private final List<Fragment> listFragment = new ArrayList<>();
private final List<String> listTitle = new ArrayList<>();
public ViewPageAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return listFragment.get(position);
}
#Override
public int getCount() {
return listTitle.size();
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
return listTitle.get(position);
}
public void AddFragment(Fragment fragment, String title){
listFragment.add(fragment);
listTitle.add(title);
}
}
How to send title onto PostFragment and TextFragment into viewpager
I am a java-illiterate, and still trying to develop a app for my personal use.
I have started with android-studio's "Tabbed-Activity", and mostly unaltered except a fragment and a bundle in MainActivity.
Here are my codes:
MainActivity
public class MainActivity extends AppCompatActivity {
private static final int REQUEST_PERMISSIONS_REQUEST_CODE = 34;
private static final String TAG = MainActivity.class.getSimpleName();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//FloatingActionButton fab = findViewById(R.id.fab);
Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment SunFragment = new SunFragment();
SunFragment.setArguments(bundle);
setContentView(R.layout.activity_main);
SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
ViewPager viewPager = findViewById(R.id.view_pager);
viewPager.setAdapter(sectionsPagerAdapter);
TabLayout tabs = findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
}
}
SectionsPagerAdapter
public class SectionsPagerAdapter extends FragmentPagerAdapter {
#StringRes
private static final int[] TAB_TITLES = new int[]{R.string.tab_text_1, R.string.tab_text_2, R.string.tab_text_3};
private final Context mContext;
public SectionsPagerAdapter(Context context, FragmentManager fm) {
super(fm);
mContext = context;
}
#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(position + 1);
switch (position) {
case 0:
return new SunFragment();
//return PlaceholderFragment.newInstance(pos + 5);
case 1:
return PlaceholderFragment.newInstance(1);
//return SecondFragment.newInstance();
//return PlaceholderFragment.newInstance(pos + 1);
default:
return PlaceholderFragment.newInstance(2);
}
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
return mContext.getResources().getString(TAB_TITLES[position]);
}
#Override
public int getCount() {
// Show 2 total pages.
return 3;
}
}
And finally, The SunFragment, where I want my bundled data from MainActivity:
public class SunFragment extends Fragment {
List<SunSession> sunsList;
Typeface sunfont;
Double Dlat;
Double Dlang;
//to be called by the MainActivity
public SunFragment() {
// Required empty public constructor
}
private static final String KEY_LOCATION_NAME = "location_name";
public String TAG ="SunFragment";
public String location;//="No location name found";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Retrieve location and camera position from saved instance state.
if (savedInstanceState != null) {
location = savedInstanceState.getCharSequence(KEY_LOCATION_NAME).toString();
System.out.println("OnCreate location "+location);
// Dlat = getArguments().getDouble("loclat");
//Dlang = getArguments().getDouble("loclang");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_sun, container, false);
//onSaveInstanceState(new Bundle());
if (getArguments() != null) {
Dlat = getArguments().getDouble("loclat");
Dlang = getArguments().getDouble("loclang");
} else {
Dlat=23.1;
Dlang=79.9864;
}
Log.e("Lat", Double.toString(Dlat));
I have followed this blog to make it, but no value is passed. Kindly help.
NB. This is a better described, and detailed question of my earlier question, which I understand, needs more code to be shown.
In your MainActivity, your sunFragment is unused. Remove this part:
/*Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment SunFragment = new SunFragment();
SunFragment.setArguments(bundle);*/
You have to set bundle to fragment inside your SectionsPagerAdapter
case 0:
Bundle bundle = new Bundle();
bundle.putDouble("loclat", 25.4358);
bundle.putDouble("loclang",81.8463);
Fragment sunFragment = new SunFragment();
sunFragment.setArguments(bundle);
return sunFragment;
But if you need to set the bundle to fragment from MainActivity. Then use a callback in that purpose.
This way you can pass data from your mainActivity to fragment
MainActivity onCreate method
adapter = new Adapter(getChildFragmentManager());
SquadsTeamListFragment teamA =
SquadsTeamListFragment.newInstance(teamAData,teamBData
adapter.addFragment(teamA, teamAName);
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
use this adapter in your main activity
static class Adapter extends FragmentStatePagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
Adapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position){
return mFragmentTitleList.get(position);
}
}
receive data to fragment (SquadsTeamListFragment .java)
public static SquadsTeamListFragment newInstance(String playerList, String
oppPlayerList) {
SquadsTeamListFragment fragment = new SquadsTeamListFragment();
Bundle args = new Bundle();
args.putString(ARG_TEAM_DATA, playerList);
args.putString(ARG_OPP_TEAM_DATA, oppPlayerList);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
playerList = getArguments().getString(ARG_TEAM_DATA);
oppPlayerList = getArguments().getString(ARG_OPP_TEAM_DATA);
}
}
Friends, I've spent enough time to find an answer to my question(here and on android's site) But no luck.
Here is the logic:
From DialogFragment upon finishing putting user's data he clicks OK button:
import de.greenrobot.event.EventBus;
...
public class AddDialogFragment extends DialogFragment implements
DialogInterface.OnClickListener {
...
public void onClick(DialogInterface dialog, int which) {
StringBuilder date = new StringBuilder(today.getText().subSequence(0,
today.getText().length()));
date = (date.toString().equals(getString(R.string.today))) ? new StringBuilder("20150104") : date;
int weight = 89;
String[] bsi = rb.getSelectedItems();
String[] gsi = rg.getSelectedItems();
DatabaseManipulation dm = new DatabaseManipulation(getActivity());
dm.run(date, weight, bsi, gsi);
dm.destroy();
DialogDataModel toSend = new DialogDataModel(weight, date.toString(), bsi, gsi);
/*
Context activity = getActivity();
if (activity instanceof WDActivity)
((WDActivity) activity).updateListItemFragment();
*/
EventBus.getDefault().post(new UpdateItemEvent(toSend));
Log.d(LOG_TAG, "send event");
Toast.makeText(getActivity(), R.string.saved_data, Toast.LENGTH_LONG).show();
}
...
Event is successfully sent to Adapter class which is registered for receiving this event:
...
import de.greenrobot.event.EventBus;
public class ItemsAdapter extends BaseAdapter implements ListAdapter {
private static final String LOG_TAG = "Logs";
private ArrayList<DialogDataModel> list = new ArrayList<DialogDataModel>();
private Context activity;
public ItemsAdapter (ArrayList<DialogDataModel> list, Context context) {
this.list = list;
this.activity = context;
registerEventBus();
}
#Override
public int getCount() {
return list.size();
}
#Override
public Object getItem(int pos) {
return list.get(pos);
}
#Override
public long getItemId(int pos) {
return pos;
//just return 0 if your list items do not have an Id variable.
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.row_item, null);
}
DialogDataModel curData = list.get(position);
TextView itemDate = (TextView)view.findViewById(R.id.item_date);
itemDate.setText(curData.getDate());
TextView itemWeight = (TextView)view.findViewById(R.id.item_weight);
itemWeight.setText( Integer.toString(curData.getWeight()) );
TextView itemEvents = (TextView)view.findViewById(R.id.item_events);
itemEvents.setText(curData.getEventsShort());
//Handle buttons and add onClickListeners
ImageButton editBtn = (ImageButton)view.findViewById(R.id.item_edit_btn);
editBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (activity instanceof WDActivity)
((WDActivity) activity).AddNewData(v, list.get(position));
notifyDataSetChanged();
}
});
ImageButton deleteBtn = (ImageButton) view.findViewById(R.id.item_delete_btn);
deleteBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String date = list.get(position).getDate();
DatabaseManipulation dm = new DatabaseManipulation(activity);
dm.deleteItem(date);
dm.destroy();
list.remove(position);
notifyDataSetChanged();
}
});
return view;
}
public void registerEventBus(){
if (!EventBus.getDefault().isRegistered(this)) EventBus.getDefault().register(this);
Log.d(LOG_TAG, "Registred from adapter");
}
public void unregisterEventBus(){
EventBus.getDefault().unregister(this);
}
public void onEventMainThread(UpdateItemEvent event) {
Log.d(LOG_TAG, "Event fired!");
list = DialogDataModel.replaceFieldsInArray(list,event.getModel());
notifyDataSetChanged();
}
}
After clicking OK in dialog window the user sees the list of items and the item he's updated is up to date. Without this logic he sees the old version of this item item in the list and to refresh the list he needs to relaunch the app.
Yes, it's working with EventBus.
But as you can see here in the class there is no place for unregistering it from listening for UpdateItemEvent. Since there are no destructors in java(I don't believe that garbage collector should do this for me) I should handle this. Moreover the class registeres as listener in constructor (it happens several times, that's why you see this ugly if statement(if (!EventBus.getDefault().isRegistered(this))) You may ask me why not getting this adapter through Activity (there is the only one in the app) I tried building a chain AddDialogFragment -> WDActivity -> PlaceholderFragment -> ItemsAdapter
//AddDialogFragment
Context activity = getActivity();
if (activity instanceof WDActivity)
((WDActivity) activity).updateListItemFragment();
//WDActivity --beginTransaction().replace does not work here
...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_wd);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
}
...
public void updateListItemFragment() {
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.Fragment currentFragment = fragmentManager.findFragmentById(R.id.container);
if (currentFragment instanceof PlaceholderFragment && currentFragment != null) {
fragmentManager.beginTransaction().remove(currentFragment).commit();
fragmentManager.beginTransaction().add(R.id.container, currentFragment).commit();
((PlaceholderFragment)currentFragment).fillList();
}
//PlaceholderFragment
public class PlaceholderFragment extends Fragment {
private static final String LOG_TAG = "Logs";
private static final String ARG_SECTION_NUMBER = "section_number";
private ListView listViewItem;
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(getArguments().getInt(ARG_SECTION_NUMBER)==1)
return onCreateViewInputChart(inflater, container, savedInstanceState);
if(getArguments().getInt(ARG_SECTION_NUMBER)==2)
return onCreateViewManual(inflater, container, savedInstanceState);
return onCreateViewInputData(inflater, container, savedInstanceState);
}
private View onCreateViewManual(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_howto, container, false);
return rootView;
}
private View onCreateViewInputData(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_list_data, container, false);
findViewsByIdListItem(rootView);
fillList();
return rootView;
}
private View onCreateViewInputChart(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_chart, container, false);
return rootView;
}
//listViewItems
private void findViewsByIdListItem(View v) {
listViewItem = (ListView) v.findViewById(R.id.listViewItems);
}
public void fillList(){
Context activity = getActivity();
DatabaseManipulation dm = new DatabaseManipulation(activity);
ArrayList<DialogDataModel> aldm = dm.getItemsList();
dm.destroy();
ItemsAdapter innerAdapter = new ItemsAdapter(aldm, activity);
listViewItem.setAdapter(innerAdapter);
( (BaseAdapter) listViewItem.getAdapter() ).notifyDataSetChanged();
}
#Override
public void onAttach(Context activity) {
super.onAttach(activity);
}
#Override
public void onDetach(){
super.onDetach();
}
}
//SectionsPagerAdapter - just for your information
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 PlaceholderFragment.newInstance(position);
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Enter your data";
case 1:
return "Chart";
case 2:
return "How to use it";
}
return null;
}
}
//ItemsAdapter is placed higher
This did not work. Finally I found out that the bottleneck is in linking PlaceholderFragment and ListAdapter: listViewItem is null everywhere except onCreateViewInputData. I could not figure out why. Google didn't give me the answer and I took it as a magic. Btw due to this feature I cannot use PlaceholderFragment's onAttach and onDetach for saying ItemsAdapter to register/unregister for receiving the event. This:
#Override
public void onAttach(Context activity) {
super.onAttach(activity);
( (ItemsAdapter) listViewItem.getAdapter() ).registerEventBus();
}
doesn't work for the same reason listViewItem is null. Maybe there is some way to manage with this more accurately?
Finally I cope with this: the bottleneck is in linking PlaceholderFragment and ListAdapter: listViewItem is null everywhere except onCreateViewInputData . Below is rewised SectionsPagerAdapter:
public class SectionsPagerAdapter extends FragmentPagerAdapter {
Context activity;
SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
public SectionsPagerAdapter(FragmentManager fm, Context activity) {
super(fm);
this.activity = activity;
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
return PlaceholderFragment.newInstance(position);
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return activity.getString(R.string.chart);
case 1:
return activity.getString(R.string.weight_diary);
case 2:
return activity.getString(R.string.how_to);
}
return null;
}
#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);
//maybe use adapater.getRegisteredFragment(viewPager.getCurrentItem());
}
}
and here is my call to the widget in the one of 3 fragments:
public void updateListItemFragment() {
android.support.v4.app.Fragment inputData = mSectionsPagerAdapter.getRegisteredFragment(1);
ListView lv = ((PlaceholderFragment)inputData).listViewItem;
//for test purposes I refill listview with no items - here you need to hand filled BaseAdapter instance: CustomAdapter innerAdapter = new CustomAdapter(ArrayList<yourDataModel>, getContext());
lv.setAdapter(null);
}
And as you've may already wondered there is no need for event bus anymore. Btw if the fragment is not crated yet you need to check it: details are here. Thanks to CommonsWare for quik reply and advice.
I have a ViewPager with fragments in my activity, each page has a textview, I want to change the text of the textview from the onCreate method in the activity that contains the viewpager. How should I go about doing that?
below is the code that would return a null object exception:
Fragment:
public class MyFragment extends Fragment {
private TextView textView;
public static MyFragment getInstance(){
return new MyFragment();
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_layout, container, false);
textView = (TextView) rootView.findViewById(R.id.textView);
return rootView;
}
public void setText(String text){
textView.setText(text);
}
}
Adapter:
public class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return MyFragment.getInstance();
}
#Override
public int getCount() {
return 3;
}
}
Activity onCreate:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
final ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
MyFragment fragment = (MyFragment) adapter.getItem(0);
fragment.setText("Altered"); // and this returns null pointer exception
}
Thank you!
Most FragmentPagerAdapters will have an addFragment method and will keep track various fragments that are added to it via an internal object:
public class MyPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments = new ArrayList<>();
private final List<String> mFragmentTitles = new ArrayList<>();
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment, String title) {
mFragments.add(fragment);
mFragmentTitles.add(title);
}
#Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
#Override
public int getCount() {
return mFragments.size();
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitles.get(position);
}
}
As it stands, your implementation of getItem returns a new instance of MyFragment every time it is called. As such, MyFragment fragment = (MyFragment) adapter.getItem(0); is a new instance that will never be loaded into the ViewPager, will never be inflated, and hence has a null textView reference.
The other issue is that within the onCreate of your activity, the fragments have not yet been inflated, so the textView will be null unless you delay the call:
final MyFragment fragment = (MyFragment) mPagerAdapter.getItem(0);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
fragment.setText("Altered");
}
}, 100);
But really, why not just set it to the correct value when it is initialized?
Try This
Fragment:
public class MyFragment extends Fragment {
private TextView textView;
private String Text;
public MyFragment (String Text){
this.Text=Text;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_layout, container, false);
textView = (TextView) rootView.findViewById(R.id.textView);
textView.setText(Text);
return rootView;
}
}
Adapter :
public class ViewPagerAdapter extends FragmentPagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return new MyFragment("Altered");
}
#Override
public int getCount() {
return 3;
}
}
Activity onCreate:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
final ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
}
I have a App with a Slidingmenu where i can pick different Fragment, which displays different kind of ListFragments.
The ListFragments will be filled by JSON from my Database Server.
If you Click on one of the Listitems, a new Fragment is shown which contains more Details about the selected Listitem.
public void updateList(final Activity a, final ListFragment L) {
adapter = new SimpleAdapter(a, mCommentList,
R.layout.single_comment, new String[] {TAG_PIC_ID,TAG_CATEGORY, TAG_ACTIVITY, TAG_DATUM, TAG_AKTUSR, TAG_MAXUSR, TAG_GENDER, /*TAG_POST_ID,*/ TAG_TITLE, TAG_MESSAGE,
TAG_USERNAME }, new int[] { R.id.imgrow, R.id.category, R.id.activity/*R.id.id*/ , R.id.datum, R.id.aktusr, R.id.maxusr, R.id.gender, /*R.id.category,*/ R.id.title, R.id.message,
R.id.username });
L.setListAdapter(adapter);
ListView lv = L.getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
int intid = (int)id;
Details nextFrag= new Details();
L.getFragmentManager().beginTransaction()
.replace(R.id.frame_container, nextFrag, "Test")
.addToBackStack(null)
.commit();
}
});
}
When i call the function from a "single" fragment its no problem and the DetailPage is shown.
The Problem is when i call the function from a TabbedActivity with a SectionsPagerAdapter.
The TabbedActivity
package info.androidhive.slidingmenu;
public class TabbedActivity extends Fragment {
SectionsPagerAdapter mSectionsPagerAdapter;
public static final String TAG = TabbedActivity.class.getSimpleName();
ViewPager mViewPager;
public static TabbedActivity newInstance() {
return new TabbedActivity();
}
#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.activity_item_one, container, false);
mSectionsPagerAdapter = new SectionsPagerAdapter(
getChildFragmentManager());
mViewPager = (ViewPager) v.findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
return v;
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment = new newEntrys();
switch (position) {
case 0:
fragment = new newEntrys();
break;
case 1:
fragment = new oldEntrys();
break;
default:
break;
}
return fragment;
}
#Override
public int getCount() {
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return "Aktuelle Einträge";
case 1:
return "Vergangene Einträge";
}
return null;
}
}}
The TabbedActivity contains the 2 Fragments newEntry and oldEntry which are nearly equal.
package info.androidhive.slidingmenu.fragments;
public class RegisterdEvents_new extends ListFragment{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.read, container, false);
return rootView;
}
public void startTask(){
Read SO = new Read();
Load LEvt = SO.new Load(getActivity(), this, "NEW");
LEvt.execute();
}
public void onResume() {
startTask();
super.onResume();
}
}
So the function updateList above is called in
Load LEvt = SO.new Load(getActivity(), this, "NEW");
But the problem is that i always get the Error
No view found for id 0x7f0a000f (package:id/frame_container) for fragment Details{e3992e2 #0 id=0x7f0a000f Test}
Someone of you can help me to solve this problem?