So basically I have 2 Fragments - FragmentConverter and FragmentFavourites, and I have one MainActivity. I'm trying to pass 4 arrays from the first fragment to the second one using an Interface called Communicator. The specific snippets are show below:
public interface Communicator {
public void respond(String[] names, String[] codes, String[] symbols, int[] images);
}
This is a method inside FragmentFavourites:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// TODO Auto-generated method stub
String[] checkedNames = new String[counter];
String[] checkedCodes = new String[counter];
String[] checkedSymbols = new String[counter];
int[] checkedImages = new int[counter];
comm = (Communicator) getActivity();
int index = 0;
if (item.getItemId() == R.id.action_save){
for (int i=0;i<checked.size();i++){
if (checked.get(i) == true){
checkedNames[index] = names[i];
checkedCodes[index] = codes[i];
checkedSymbols[index] = symbols[i];
checkedImages[index] = images[i];
index++;
}
}
comm.respond(checkedNames, checkedCodes, checkedSymbols, checkedImages);
}
return super.onOptionsItemSelected(item);
}
This is the implemented interface method inside MainActivity:
#Override
public void respond(String[] names, String[] codes, String[] symbols,
int[] images) {
// TODO Auto-generated method stub
FragmentConverter frag = (FragmentConverter) fragmentPagerAdapter.getItem(1);
frag.changeData(names, codes, symbols, images);
}
And this is a method that collects the data in FragmentConverter:
public void changeData(String[] names, String[] codes, String[] symbols, int[] images){
this.names = names;
this.codes = codes;
this.symbols = symbols;
this.images = images;
Log.d("TEST", symbols.length + names.length + codes.length + images.length + "");
tvOneRate.setText(names[1]);
}
Now the problem is that whenever I try to change a ui component inside FragmentConverter, I get a NullPointerException, though the Log.d statement returns the correct results.
EDIT1: getItem() method of FragmentPagerAdapter:
#Override
public Fragment getItem(int i) {
// TODO Auto-generated method stub
Fragment frag = null;
if (i == 0){
frag = new FragmentFavourites();
}
if (i == 1){
frag = new FragmentConverter();
}
return frag;
}
EDITED:
When you call fragmentPagerAdapter.getItem(1) you are getting a new instance of the fragment so you are referring to a different object. this is why the view is null and you get the NullPointerException. If you need an adapter for only 2 fragments, you can try with something like that:
public class YourPagerAdapter extends android.support.v4.app.FragmentPagerAdapter {
private FragmentFavourites mFragFavourites;
private FragmentConverter mFragConverter;
public YourPagerAdapter() {
// ... your code above
this.mFragFavourites = new FragmentFavourites();
this.mFragConverter = new FragmentConverter();
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return mFragFavourites;
case 1:
return mFragConverter;
default:
return null;
}
}
}
As above carlo.marinangeli has suggested when you call fragmentPagerAdapter.getItem(1) you are getting a new instance of the fragment so you are referring to a different object
So to get same object from you adapter you need to store your object. you can try following method in your adapter -
public Fragment getFragmentAtPosition(int position) {
return registeredFragments.get(position);
}
where registeredFragments is -
private SparseArray<Fragment> registeredFragments = new SparseArray<Fragment>();
and fill this sparseArray in getItem method like below -
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
fragment = FragmentPost.newInstance(position);
registeredFragments.put(position, fragment);
return fragment;
}
return null;
}
By using fragmentPagerAdapter.getItem(pos) method I was referring to a new object every time the respond() method was called. I fixed it by using findFragmentByTag() method instead:
#Override
public void respond(String[] names, String[] codes, String[] symbols,
int[] images) {
FragmentManager manager = getSupportFragmentManager();
FragmentConverter frag = (FragmentConverter) manager.findFragmentByTag("android:switcher:" + pager.getId() + ":" + 1);
frag.changeData(names, codes, symbols, images);
}
you can get that error because you are assuming that you have got the FragmentConverter and the views associated to it.
Without a logcat it becomes a little bit difficult to help you but basically what I would like to do in a situation like this is to pass everything through the activity without letting know the existence of the other fragment to the fragments.
F1 modifies a state object into the activity
F2 has to register as a
listener to the activity (be aware that the fragment can be attached
and detached in the view pager)
The Activity as soon it receives an updated, looks for all the registered listeners and if there is someone it delivers the updated
Related
I've written a game where the user inputs the number of player and every player gets an own tab with an empty table.
Therefore I used a PagerAdapterClass (extends FragmentStatePagerAdapter) and a viewpager.
So every player has the same fragmentView.
Now the user can put variables into the table, bu everytime I switch between the tabs, the input gets lost.
Well, i 'fixed' that problem by adding this to my pageradapter:
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
}
But it's more stopping the viewpager from destroying than actually saving the data.
My main goal is to really save that stuff in that table.
I already tried https://stackoverflow.com/a/17135346/11956040 but i cannot get mContent because i cannot get the reference of the fragment, because all fragments are not created on their own but all at the same time (or something like that).
I also don't know how to set a Tag.
This way: https://stackoverflow.com/a/18993042/11956040
doesn't work for me.
MainActivity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
Toolbar toolbar = findViewById(R.id.toolbar2);
setSupportActionBar(toolbar);
...
//numPlayer = num of tabs
SectionsPagerAdapter adapter = new SectionsPagerAdapter(numPlayer, getSupportFragmentManager());
ViewPager viewPager = findViewById(R.id.view_pager);
viewPager.setAdapter(adapter);
TabLayout tabs = findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
if(numPlayer >= 5) {
tabs.setTabMode(TabLayout.MODE_SCROLLABLE);
}
}
PagerAdapter:
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
private int tabNum;
public SectionsPagerAdapter(int tabNum, FragmentManager fm) {
super(fm);
this.tabNum = tabNum;
}
#Override
public PlaceholderFragment getItem(int position) {
return PlaceholderFragment.newInstance(position);
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
int playerNum = position + 1;
return "Spieler " + playerNum;
}
#Override
public int getCount() {
// Show 2 total pages.
return tabNum;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
}
}
Fragment:
public static PlaceholderFragment newInstance(int index) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle bundle = new Bundle();
bundle.putInt("player", index);
fragment.setArguments(bundle);
return fragment;
}
There must be a solution but I cannot find it or cannot implement it.
Pls help.
Solved my problem this way:
define 2 dimensional ArrayList for rows and columns and counter for columns:
private ArrayList<ArrayList<Integer>> columnArray;
private int column;
onCreateView (for fragments) set column = 0 and add one entry with an empty list to columnArray
and set the first rowList on column index of columnArray:
pointArray.add(column, new ArrayList<Integer>());
final ArrayList<Integer> rowList = pointArray.get(column);
fill the empty rowListwith 0 (maybe it also works in an other way, but I made it this way to have on empty EditTexts a 0 and can easily replace them)
define View.OnFocusChangeListener for all EditTexts like this:
/*I dont know if I could set column final in general,
but you need to set a final int because you call this value in an inner class*/
final int pos = column
for (int i = 0; i <= getEditTexts(pos).size() - 1; i++) {
EditText editTexts = getEditTexts(pos).get(i);
final String editTextsTag = editTexts.getTag().toString();
View.OnFocusChangeListener listener = new View.OnFocusChangeListener() {
#Override
public void onFocusChange(View view, final boolean b) {
if (view.getTag().toString().equals(editTextsTag) && !b) {
//fills rowList
addEntries(pos, rowList);
//adds rowList to columnArray
columnArray.set(pos, rowList);
//save the columnsArray or use it
saveData(columnArray);
}
}
};
editTexts.setOnFocusChangeListener(listener);
define method which collects data from each cell, depending on column position (pos), add it to rowList
for example:
private void addEntries(int pos, ArrayList<Integer> rowList) {
for(int i = 0; i <= 16; i++) {
//this requires EditText_label, i made them dynamically
String edit_label = "edit_" + pos + i;
EditText editText = table.findViewWithTag(edit_label);
String mEditTextString = editText.getText().toString();
try {
int thisValue = Integer.parseInt(mEditString);
rowList.set(j, thisValue);
} catch (NumberFormatException e) {
//maybe you do not need this, but I need it for something else
int thisValue = 0;
rowList.set(j, thisValue);
}
}
}
define a method for saving the columnArray. I used an interface to give it to parent Activity: Here you can find how I made it
Otherwise you can convert the columnArray to a String and save it in a database.
NOTE
I made it with column value set beacuse I increase the value for every column I add during runtime using a method. If you just have one column, you dont need to set it. Just use 0 instead of pos, column
I'm working on an app and I have a menu with a NavigationDrawer to navigate between fragments. In one of the fragments I make a call to the backend and then save the results in a list. When I navigate to another fragment and back, the results are gone, but I'd like to save the contents of the list temporarily. I wanted to use onSaveInstanceState(), but that method doesn't seem to get called ever. I also looked if the data is still in the fields when I return to the fragment, but that also wasn't the case. I think I'm doing something wrong with the FragmentManager, but I'm not sure about it.
This is the method used for the transactions for the Fragments:
private void openFragment(Class fragmentClass) {
Fragment fragment;
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
return;
}
contentFrame.removeAllViews();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.contentFrame,fragment).commit();
}
I use a switch case to determine the Fragment's class and send that to this method.
I could probably figure out a hacky-snappy way to fix this, but I'd like to fix this without too much hacky-snappy code.
I hope someone has an idea on how to fix this. Thanks in advance.
EDIT:
Here is my fragment class:
public class LGSFragment extends Fragment {
#BindView(R.id.rvLGS)
RecyclerView rvLGS;
private List<LGS> lgsList;
private LGSAdapter adapter;
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
//I debugged here and all fields were null at this point
View view = inflater.inflate(R.layout.fragment_lgs,container,false);
ButterKnife.bind(this, view);
lgsList = new ArrayList<>();
LinearLayoutManager manager = new LinearLayoutManager(getContext());
rvLGS.setLayoutManager(manager);
adapter = new LGSAdapter(lgsList);
rvLGS.setAdapter(adapter);
getDatabaseLGSs();
return view;
}
/**
* Method to load in the LGSs from the database
*/
private void getDatabaseLGSs() {
String collection = getString(R.string.db_lgs);
FireStoreUtils.getAllDocumentsConverted(collection, LGS.class, new OperationCompletedListener() {
#Override
public void onOperationComplete(Result result, Object... data) {
if (result == Result.SUCCESS) {
lgsList.clear();
List<LGS> newLGSs = (List<LGS>) data[0];
List<String> ids = (List<String>) data[1];
int i = 0;
for (LGS lgs : newLGSs) {
lgs.setId(ids.get(i));
lgsList.add(lgs);
i++;
}
adapter.notifyDataSetChanged();
}
}
});
}
#Override
public void onSaveInstanceState(#NonNull Bundle outState) {
super.onSaveInstanceState(outState);
}
}
onSaveInstanceState is not called because there is no reason to, when you navigate between fragments, the older fragment doesn't get destroyed till the OS need the space they use (low Memory).
First of all create a back stack to keep fragments or just call addtoBackStack at the end of fragmentTransaction and then move the list initiation and data request to onCreate so it only called when the fragment is created:
lgsList = new ArrayList<>();
getDatabaseLGSs();
and after that every time you get back to fragment the view is recreated with available data.
Update:
Instead of keeping an reference on your own, you can add the fragment to the backstack and then retrieve it using corresponding tag. This let's fragmentManager manages the caching by itself. And the second time you access a fragment, it doesn't gets recreated:
#Override
public void onNavigationDrawerItemSelected(#NonNull MenuItem item) {
if (item.isChecked())
return;
item.setChecked(true);
setTitle(item.getTitle());
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
Fragment currentlyShown = fragmentManager.findFragmentByTag(currentlyShownTag);
Fragment dest;
switch (item.getItemId()){
case R.id.nav_lgs:
dest = fragmentManager.findFragmentByTag(LGSFragment.class.getName());
if (dest == null) {
Log.d("TRANSACTION", "instanciating new fragment");
dest = new LGSFragment();
currentlyShownTag = LGSFragment.class.getName();
transaction.add(R.id.contentFrame, dest, LGSFragment.class.getName());
}
break;
...
}
if(currentlyShown != null)
transaction.hide(currentlyShown);
transaction.show(dest);
transaction.commit();
drawerLayout.closeDrawers();
return true;
}
EDIT:
Although this solution works fine, this solution uses some bad practices, I recommend using the accepted solution instead.
I've solved the problem with the help of Keivan Esbati and denvercoder9 (Thanks for that!)
Since I only have 4 fragments I keep an instance of each of them in the MainActivity, I also have a variable to track the current Fragment. Everytime I open a fragment, I hide the current fragment using the FragmentManager and calling .hide() in the transaction. Then, if the Fragment is a new Fragment I call .add() in the transaction, otherwise I call .show in the transaction.
The code for the onNavigationItemSelected() method (which triggers when a user selects an item in the menu):
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
if (!item.isChecked()) {
item.setChecked(true);
setTitle(item.getTitle());
switch (item.getItemId()) {
case R.id.nav_lgs: {
if (lgsFragment == null) {
lgsFragment = new LGSFragment();
openFragment(lgsFragment, FragmentTag.LGS.toString());
} else {
openFragment(lgsFragment, "");
}
currentFragmentTag = FragmentTag.LGS;
break;
}
case R.id.nav_users: {
if (userFragment == null) {
userFragment = new UserFragment();
openFragment(userFragment, FragmentTag.USERS.toString());
} else {
openFragment(userFragment, "");
}
currentFragmentTag = FragmentTag.USERS;
break;
}
case R.id.nav_profile: {
if (profileFragment == null) {
profileFragment = new ProfileFragment();
openFragment(profileFragment, FragmentTag.PROFILE.toString());
} else {
openFragment(profileFragment, "");
}
currentFragmentTag = FragmentTag.PROFILE;
break;
}
case R.id.nav_my_lgs: {
if (myLGSFragment == null) {
myLGSFragment = new MyLGSFragment();
openFragment(myLGSFragment, FragmentTag.MY_LGS.toString());
} else {
openFragment(myLGSFragment, "");
}
currentFragmentTag = FragmentTag.MY_LGS;
break;
}
default: {
if (lgsFragment == null) {
lgsFragment = new LGSFragment();
openFragment(lgsFragment, FragmentTag.LGS.toString());
} else {
openFragment(lgsFragment, "");
}
currentFragmentTag = FragmentTag.LGS;
break;
}
}
}
drawerLayout.closeDrawers();
return true;
}
The openFragment() method used above:
private void openFragment(Fragment fragment, String tag) {
FragmentManager fragmentManager = getSupportFragmentManager();
if (currentFragmentTag != FragmentTag.NO_FRAGMENT) {
fragmentManager.beginTransaction().hide(fragmentManager.findFragmentByTag(currentFragmentTag.toString())).commit();
}
if (!tag.equals("")) {
fragmentManager.beginTransaction().add(R.id.contentFrame,fragment,tag).commit();
} else {
fragmentManager.beginTransaction().show(fragment).commit();
}
}
Set up in onCreate():
currentFragmentTag = FragmentTag.NO_FRAGMENT;
if (lgsFragment == null) {
lgsFragment = new LGSFragment();
openFragment(lgsFragment, FragmentTag.LGS.toString());
} else {
openFragment(lgsFragment, "");
}
currentFragmentTag = FragmentTag.LGS;
I'm trying to replace fragments in ViewPager, but I'm facing a problem I've been unable to fix for several days. The relevant code and specific problem, as I understand it, are described below:
public class ViewPageAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
FragmentManager mFragmentManager;
Fragment0 currentFragment0;
Fragment1 currentFragment1;
Fragment2 currentFragment2;
boolean getItemNeverCalled = true;
public ViewPageAdapter(FragmentManager fm, int numOfTabs){
super(fm);
mFragmentManager = fm;
this.mNumOfTabs = numOfTabs;
}
#Override
public Fragment getItem(int position){
switch (position){
case 0:
if(currentFragment0 == null){
Fragment0 tab0 = new Fragment0();
currentFragment0 = tab0;
return currentFragment0;
}
else {
mFragmentManager.beginTransaction().remove(currentFragment0).commit();
int value = selectedPlant.getMoistureFrag().getStat().getOptimalLevel();
currentFragment0 = Fragment0.newInstance(key0, value);
notifyDataSetChanged(); // calls getItem(0).
return currentFragment0;
}
case 1:
if(currentFragment1 == null){
LightFragment tab1 = new Fragment1();
currentFragment1 = tab1;
return currentFragment1;
}
else {
mFragmentManager.beginTransaction().remove(currentFragment1).commit();
int value = selectedPlant.getLightFrag().getStat().getOptimalLevel();
currentFragment1 = currentFragment1.newInstance(key1, value);
notifyDataSetChanged();
return currentFragment1;
}
case 2:
if(currentFragment2 == null){
Fragment2 tab2 = new Fragment2();
currentFragment2 = tab2;
return currentFragment2;
}
else {
mFragmentManager.beginTransaction().remove(currentFragment2).commit();
int value = selectedPlant.getTempFrag().getStat().getOptimalLevel();
currentFragment2 = Fragment2.newInstance(key2, value);
notifyDataSetChanged();
return currentFragment2;
}
default:
return null;
}
}
#Override
public int getCount(){
return mNumOfTabs;
}
#Override
public int getItemPosition(Object object){
return POSITION_NONE;
}
I've overriden the getItemPosition(Object object) method to always return POSITION_NONE, and called notifyDataSetChanged() when appropriate (I think). What ends up happening is that notifyDataSetChanged() calls getItem(0), which calls `notifyDataSethanged()... and so on. This causes a TransactionTooLargeException and crashes the app.
Just to give some background to the if/else statements in each case: the if is meant to load a blank Moisture/Light/etc Fragment onto the screen. This is intended to happen on start-up. The else statement is executed when a user presses on a item in the navigation drawer, which has some data. This data is then extracted and set as arguments for the fragments that are meant to replace the initial blank fragment.
I genuinely appreciate any help. This problem is driving me crazy.
Why in the world are you recreating fragments, when you can just update the old ones?
Also, when you are calling notifyDataSetChanged during getItem then you are forcing a new call to getItem which will force a new call...so you are actually creating a circular call!
Since you are always keeping the same fragment class in each position, and you are holding on to the fragment, then you should not replace fragment. Just change the fragment you are holding to show the new values. The code you are using is only needed if you want to change different fragment classes for position.
Good day all,
I have an issue where my activity is making a network call and when the network call is completed, it makes some changes in the activity using the data from the JSON object received from the call, it then passes the object down to the fragments in the same activity. These fragments are in a TabLayout.
I had this same issue which I asked here at this SO Question That sorted it out but I seem to be having the same issue, even after it worked for a little bit after not changing anything significant. I was just adding more fields I wanted to change?
The issue I have is that if I put a System.out.println() it prints out the correct data. The minute I want to set say a TextView with the data I receive in the Fragment the app Crashes with Nullpointer. When I debug it with the Debug in Android studio, the TextView I'm setting is always null for some reason.
Activity Code that does the initial Network call:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listings);
ButterKnife.bind(this);
setSupportActionBar(toolbar);
handleIntent(getIntent());
}
private void handleIntent(Intent aIntent) {
if (aIntent != null) {
String tradeType = aIntent.getStringExtra("itemType");
String tradeId = aIntent.getStringExtra("itemId");
presenter = new ItemPresenterImpl(this, ItemBuyNowActivity.this);
presenter.doListingServiceCall(tradeId); // <------- This is the where I send the Trade Id so I can do the network call.
} else {
System.out.println("Intent is null in " + ItemBuyNowActivity.class.getSimpleName());
}
}
Interface between Activity and Presenter:
public interface ItemPresenter {
void doListingServiceCall(String itemId); //<------- Comes to this Interface
void doToolbarBackgroundImageCall(TradeItem aTradeItem);
}
Class the implements the Presenter:
#Override
public void doListingServiceCall(String aItemId) { // <------- This is where the network call starts
String homeURL = BobeApplication.getInstance().getWsURL() + mContext.getString(R.string.ws_url_item) + aItemId;
BobeJSONRequest jsObjRequest = new BobeJSONRequest(Request.Method.GET, homeURL, null, this, this);
VolleySingleton.getInstance().addToRequestQueue(jsObjRequest, "ListingRequest");
}
#Override
public void doToolbarBackgroundImageCall(TradeItem aTradeItem) {
ImageRequest request = new ImageRequest(aTradeItem.getItem().getImageUrl(),
new Response.Listener<Bitmap>() {
#Override
public void onResponse(Bitmap bitmap) {
Drawable drawable = new BitmapDrawable(mContext.getResources(), bitmap);
mItemView.loadBackgroundImage(drawable);
}
}, 0, 0, null,
new Response.ErrorListener() {
public void onErrorResponse(VolleyError error) {
mItemView.displayErrorMessage(VolleyErrorHelper.getErrorType(error, mContext) + " occurred downloading background image");
}
});
VolleySingleton.getInstance().addToRequestQueue(request, "ListItemToolbarBackgroundImageRequest");
}
#Override
public void onResponse(Object response) {
Gson gson = new Gson();
TradeItem tradeItem = gson.fromJson(response.toString(), TradeItem.class);
mItemView.populateListViews(tradeItem); // <------- This is the where I send the Object so the views in the activity can be manipulated
doToolbarBackgroundImageCall(tradeItem);
}
Method in the Activity that handles
#Override
public void populateListViews(TradeItem aTradeItem) {
mOverviewPresenter = new OverviewPresenterImpl(new OverviewListItemFragment(), aTradeItem);
OverviewListItemFragment.setData(aTradeItem); //<------- This is the where I send the Object to the fragment so i can manipulate the views in the fragment
}
class TabAdapter extends FragmentPagerAdapter {
public TabAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment = null;
if (position == 0) {
fragment = new OverviewListItemFragment();
}
if (position == 1) {
fragment = new DescriptionListItemFragment();
}
if (position == 2) {
fragment = new ShippingListItemFragment();
}
if (position == 3) {
fragment = new PaymentListItemFragment();
}
return fragment;
}
#Override
public int getCount() {
return 4;
}
#Override
public CharSequence getPageTitle(int position) {
if (position == 0) {
return "Overview";
}
if (position == 1) {
return "Description";
}
if (position == 2) {
return "Shipping";
}
if (position == 3) {
return "Payment";
}
return null;
}
}
The Fragment that receives the data:
public class OverviewListItemFragment extends Fragment implements OverviewView {
private static TextView mOverViewHeading;
public OverviewListItemFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.overview_list_item_fragment, container, false);
mOverViewHeading = (TextView) view.findViewById(R.id.frag_overview_heading_textview);
return view;
}
#Override
public void populateOverviewViews(final TradeItem aTradeItem) {
System.out.println("Overview Trade Object title is:" + aTradeItem.getItem().getTradeTitle()); // <------- This is print statement works 100% but when I try setting mOverViewHeading to the text in aTradeItem.getItem().getTradeTitle() I get a Null pointer Exception.
}
public static void setData(TradeItem aTradeItem) {
System.out.println("Overview Trade Object title is:" + aTradeItem.getItem().getTradeTitle()); // <------- This is print statement works 100% but when I try setting mOverViewHeading to the text in aTradeItem.getItem().getTradeTitle() I get a Null pointer Exception.
mOverViewHeading.setText(aTradeItem.getItem().getTradeTitle());// <------- This is where it crashes and mOverViewHeading is still null at this point.
}
}
EDIT: Sorry I forgot the LogCat:
02-05 17:08:21.554 30512-30512/com.example.app E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.app.ui.fragments.OverviewListItemFragment.setData(OverviewListItemFragment.java:46)
at com.example.app.ui.activities.ItemBuyNowActivity.populateListViews(ItemBuyNowActivity.java:95)
at com.example.app.listing.ItemPresenterImpl.onResponse(ItemPresenterImpl.java:62)
at com.android.volley.toolbox.JsonRequest.deliverResponse(JsonRequest.java:65)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)
My thinking is that the view I'm trying to set isn't "Active" (if thats the right word) at the time it receives the data, because when I run the debugger with a break point at the method that receives the data in the Fragment, the mOverViewHeading TextView id is null, even though I have the findViewById in the onCreate, also tried placing it in the onCreateView() but both times failed. I also tried placing the findViewById in the same method that gets called when the response is successful but before I try setting the setText() on the TextView.
Thank you
OverviewListItemFragment I assume this is not your added fragment instance, but the class.
I suggest the following changes: remove static from setData and your TextView, leave it, if you really know how it works. I don't think it is necessary or recommendable.
private OverviewListItemFragment mFrag; //declare globally
mFrag = new OverviewListItemFragment();
//if you do not want to add it now, ignore the following line
getSupportFragmentManager().beginTransaction().add(R.id.yourContainer, mFrag, "mFrag").commit();
now call mFrag.setData everytime you want to set your data. Check if your mFrag is null, then reinitialize, and maybe re-add, or whatever you want to do.
Edit: Now that I know that you use a ViewPager, I suggest the following:
Do the above. I don't think it is recommendable to have static methods in this Context. You get an error because you are trying to reach a TextView in your Fragment. This was initialized in a ViewPager/PagerAdapter, and the PagerAdapter holds the reference to the used instance of your fragment.
You can access your used fragment through
Fragment mFragment = pagerAdapter.getFragment(0); //frag at position 0
with some casting, you will be able to find your (now NOT static) method:
((OverviewListItemFragment)pagerAdapter.getFragment(0)).setData(YOUR_DATA);
Please add some try/catch. check if your fragment is null, because it is possible that your fragment is recycled in the FragmentPagerAdapter, because it reached the offset. Another way to achieve this, would be to store your required data, and update it everytime your fragment gets visible as described here.
Edit 2: Obviously, You'll need some changed in your Adapter:
I would recommend creating an array containing your fragment in the constructor:
//global in your adapter:
private Fragment[] fragments;
public CustomPagerAdapter(FragmentManager fm) {
super(fm);
fragments = new GameFragment[4];
fragments[0] = new MyFragment();
fragments[1] = new SecondFragment();
....
}
public Fragment getItem(int position) {
return fragments[position];
}
public Fragment getFragment(int position) {
return fragments[position];
}
I have a main activity which creates fragments using the following code
private void launchFragment(int pos)
{
Fragment f = null;
String title = null;
if (pos == 1)
{
title = "Friends";
f = new FriendList();
}
else if (pos == 2)
{
title = "Notes";
f = new NoteList();
}
else if (pos == 3)
{
title = "Projects";
f = new ProjectList();
}
else if (pos == 5)
{
title = "About";
f = new AboutUs();
}
else if (pos == 6)
{
startActivity(new Intent(this, Login.class));
finish();
}
if (f != null)
{
while (getSupportFragmentManager().getBackStackEntryCount() > 0)
{
getSupportFragmentManager().popBackStackImmediate();
}
getSupportFragmentManager().beginTransaction()
.replace(R.id.content_frame, f).addToBackStack(title)
.commit();
}
}
Here is the code of a fragment.
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.group_chat, null);
loadConversationList();
contactName = this.getArguments().getString("contactusername");
contactId = this.getArguments().getString("contactid");
ListView list = (ListView) v.findViewById(R.id.list);
adp = new ChatAdapter();
list.setAdapter(adp);
list.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
list.setStackFromBottom(true);
txt = (EditText) v.findViewById(R.id.txt);
txt.setInputType(InputType.TYPE_CLASS_TEXT
| InputType.TYPE_TEXT_FLAG_MULTI_LINE);
setTouchNClick(v.findViewById(R.id.btnCamera));
setTouchNClick(v.findViewById(R.id.btnSend));
return v;
}
I want to call a method in above fragment class. I was not able to do this as I have not given id of the fragment in the XML file. I am not loading the static fragment using XML. Therefore, I don't have Id.
I have already seen this and this questions on the StackOverFlow, but they are not solving my problem.
Kindly help if anyone knows how to tackle this scenario.
First of all make all your fragments implement an interface. This interface will return a String (for example) which will identify your fragment, and then cast your fragment to it after getting the fragment using findFragmentById() as follows:
Create your interface
public interface IFragmentName
{
public String getFragmentName();
}
Implement your interface (for example in NoteList)
public NoteList extends Fragment implements IFragmentName
{
//Do your stuff...
public String getFragmentName()
{
return "NoteList";
}
}
After this get your current fragment from your activity
IFragmentName myFragment = (IFragmentName) getSupportFragmentManager().findFragmentById(R.id.content_frame);
Finally check your getFragmentName() value and cast to the fragment you want:
if(myFragment.getFragmentName().equals("NoteList")
{
NoteList myNoteListFragment = (NoteList) myFragment;
myNoteListFragment.callMyMethod(); //here you call the method of your current Fragment.
}
I have coded these snippets without any IDE so maybe I have missed a semicolon or something like that :)
Hope it helps
I know I am too late for the party. But this will be useful for others.
If at all you are using ViewPager to render the fragment use this code in your parent Activity.
Check Solution here