I'm using 3 Fragments inside a Viewpager, the problem is that I am loading big data in an Asynctask and loaders. On devices like HTC one, it works fine, however, on low-end devices, it takes a lot of time. This is mainly because when I implement the pagerAdapter, I put the Fragments inside an ArrayList, this force the fragments instantiate when the main activity is loaded. What I need is that it just "load" the first fragment (main) and when the user Swype, load the other fragment. its any way to achieve this? this is my pageAdapater
public class PagerAdapter extends FragmentPagerAdapter {
private final ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
// private final ArrayList<String> titulos = new ArrayList<String>();
// private int NUM_PAGES =0;
public PagerAdapter(FragmentManager manager,int num_pages) {
super(manager);
// this.NUM_PAGES = num_pages;
}
public void addFragment(Fragment fragment,String title) {
mFragments.add(fragment);
notifyDataSetChanged();
}
#Override
public int getCount() {
//return NUM_PAGES;
return mFragments.size();
}
#Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
}
The above method from Sun did not work for me (maybe it does for you), but I thought I would share my edit of his method also. Very good method by the way Sun!
private boolean _hasLoadedOnce= false; // your boolean field
#Override
public void setUserVisibleHint(boolean isFragmentVisible_) {
super.setUserVisibleHint(true);
if (this.isVisible()) {
// we check that the fragment is becoming visible
if (isFragmentVisible_ && !_hasLoadedOnce) {
new NetCheck().execute();
_hasLoadedOnce = true;
}
}
}
I'm gonna add my solution here since I faced a similar issue. My asynchronous task wasn't loading huge amounts of data, but it prevents unnecessary network calls. Here's what I added in my Fragment:
private boolean _hasLoadedOnce= false; // your boolean field
#Override
public void setUserVisibleHint(boolean isFragmentVisible_) {
super.setUserVisibleHint(isVisibleToUser);
if (this.isVisible()) {
// we check that the fragment is becoming visible
if (!isFragmentVisible_ && !_hasLoadedOnce) {
//run your async task here since the user has just focused on your fragment
_hasLoadedOnce = true;
}
}
}
With the above code, your Fragment will be loaded, but your async task will not run until the user actually scrolls to the Fragment for the first time. Once displayed, your async task will run for the first time automatically. Then you can provide a way to load more data via a button or pull to refresh. The above Fragment was in my ViewPager and seemed to work fine.
Slightly modified version to fix potential NPE caused by some views not fully initialised
private boolean _hasLoadedOnce= false; // your boolean field
#Override
public void setUserVisibleHint(boolean isFragmentVisible_) {
super.setUserVisibleHint(isVisibleToUser);
if (this.isVisible()) {
// we check that the fragment is becoming visible
if (!isFragmentVisible_ && !_hasLoadedOnce) {
new Handler().post(() -> {
makeAsyncRequest();//do your asyn stuffs
_hasLoadedOnce = true;
});
}
}
}
Use fragmentStatePageAdapter if you have a lot of pages and you want to destroy them when not visible.
It has implemented a setMenuVisibility(boolean menuVisible) when fragment becomes visible, so use that.
I might be late for the party but here's my solution and it works as expected. In all of your child fragments create a boolean variable:
private boolean loadFragmentExecuted = false;
in the child fragments create a generic method called loadFragment and move all of the logic you added in onCreateView to that method:
public void loadFragment()
{
if(!loadFragmentExecuted)
{
//Add your logic to manipulate the UI or load data etc...
loadFragmentExecuted = true;
}
}
in your pageview logic create the fragments dynamically like:
//add the fragment
String fragmentName = "com.something." + fragmentId;
//check if the class exists
try
{
Class myFragmentClass = Class.forName(fragmentName);
Fragment myFragment = (Fragment) myFragmentClass.newInstance();
mFragments.add(myFragment);
}
catch (ClassNotFoundException e)
{
e.printStackTrace();
}
catch (IllegalAccessException e)
{
e.printStackTrace();
}
catch (InstantiationException e)
{
e.printStackTrace();
}
then set your pager adapter and attach a tablayout with it:
//set our pager adapter that contains different fragments
mPagerAdapter = new BasePagerAdapter(mFragmentManager, mFragments);
//link the adapter to the viewpager
mViewPager.setAdapter(mPagerAdapter);
//cache fragments
int limit = (mPagerAdapter.getCount() > 0 ? mPagerAdapter.getCount() : 1);
mViewPager.setOffscreenPageLimit(limit);
//add the page listner to the viewPager and link it to the tabLayout
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(mTabLayout));
//on tab selected select current viewpager item
mTabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
{
#Override
public void onTabSelected(TabLayout.Tab tab)
{
mViewPager.setCurrentItem(tab.getPosition());
//get fragment for the selected tab
Fragment f = mPagerAdapter.getItem(tab.getPosition());
//load the content of the fragment
try
{
Class c = f.getClass();
Method loadFragment = c.getMethod("loadFragment");
loadFragment.invoke(f);
}
catch (IllegalAccessException e){}
catch (InvocationTargetException e){}
catch (NoSuchMethodException e){}
}
#Override
public void onTabUnselected(TabLayout.Tab tab)
{
}
#Override
public void onTabReselected(TabLayout.Tab tab)
{
}
});
Related
I have a fragment which displays a popup when the user is successfully logged in. If I navigate to a new fragment and come back, the popup with the previous username is shown again. I fixed this problem using SingleLiveEvent, but I now have to refactor my code to use MediatorLiveData as my data can come from 2 sources (remote and database), and it is not compatible with SingleLiveEvent.
I tried using an event wrapper and removing observers on onDestroyView() but so far nothing is working, the livedata onChanged function keeps getting called when I move back to the fragment. Here is some of my fragment:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
binding = FragmentDashboardBinding.inflate(inflater, container, false);
binding.setLifecycleOwner(getActivity());
//Get the attendanceViewModel for registering attendance
attendanceViewModel = ViewModelProviders.of(this).get(AttendanceViewModel.class);
attendanceViewModel.getAttendance().observe(getViewLifecycleOwner(), attendanceAndMember -> {
if (attendanceAndMember != null && attendanceAndMember instanceof AttendanceMemberModel) {
clokedInOutMember = attendanceAndMember.member;
}
showResultClockInOutPopup();
});
return binding.getRoot();
}
private void showResultClockInOutPopup() {
clockInBuilder = new AlertDialog.Builder(getActivity());
View view = getLayoutInflater().inflate(R.layout.status_clock_in_out_popup, null);
TextView responseClockInOut = view.findViewById(R.id.responseClockInOut);
Button dismissButton = view.findViewById(R.id.dismissButton);
//Setup Popup Text
if (clokedInOutMember != null) {
if (StringToBool(clokedInOutMember.is_clocked_in_temp)) {
responseClockInOut.setText("Bienvenue " + clokedInOutMember.name + ", tu es bien enregistré(e).");
} else {
responseClockInOut.setText("Désolé de te voir partir " + clokedInOutMember.name + ", à bientôt!");
}
} else {
responseClockInOut.setText("Oups, il semblerait qu'il y ait une erreur...\n Essaye à nouveau.");
}
[..SETUP ALERTDIALOG...]
//Dismiss popup
dismissButton.setOnClickListener(v -> {
clockInResultDialog.dismiss();
clockInResultPopupShowed = false;
clokedInOutMember = null;
});
clockInResultDialog.show();
clockInResultPopupShowed = true;
}
}
#Override
public void onDestroyView() {
attendanceViewModel.getAttendance().removeObservers(this);
super.onDestroyView();
}
And here is my ViewModel, I have to use transformations as I am getting the userId from the fragment, passing to the Viewmodel which passes it to the repository for query (maybe there is a better way?):
public class AttendanceViewModel extends AndroidViewModel {
private AttendanceRepository repository = AttendanceRepository.getInstance();
public LiveData<AttendanceMemberModel> mAttendanceAndMember;
private MutableLiveData<String> mId = new MutableLiveData<>();
private MediatorLiveData<AttendanceMemberModel> mObservableAttendance = new MediatorLiveData<AttendanceMemberModel>();
{
mObservableAttendance.setValue(null);
mAttendanceAndMember = Transformations.switchMap(mId, id -> {
return repository.saveAttendance(id);
});
mObservableAttendance.addSource(mAttendanceAndMember, mObservableAttendance::setValue);
}
public AttendanceViewModel(#NonNull Application application) {
super(application);
}
public LiveData<AttendanceMemberModel> getAttendance() {
return mObservableAttendance;
}
public void setMemberId(String id) {
mId.setValue(id);
}
#Override
protected void onCleared() {
mObservableAttendance.setValue(null);
super.onCleared();
}
}
I can suggest you two ways. First create a boolean variable whether dialog is shown in Fragment and after showing dialog set it to true and before showing dialog check if dialog is shown. Second way is after showing dialog set livedata value to null and check if observer value null before showing dialog. I prefer second way.
Use anyone of them, which works and behaves according to your need.
#Override
public void onPause() {
attendanceViewModel.getAttendance().removeObservers(this);
super.onPause();
}
#Override
public void onStop() {
attendanceViewModel.getAttendance().removeObservers(this);
super.onStop();
}
Fragment Life Cycle
Have a look at the lifecycle of the fragment, it will give you bit more idea.
Let me know if this works or not.
The best way to the same is to bind your view model in OnViewCreated meathod.
#Override
public void onActivityCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
attendanceViewModel = ViewModelProviders.of(this).get(AttendanceViewModel.class);
setUpObservers();
}
private void setUpObservers() {
attendanceViewModel.getAttendance().observe(getViewLifecycleOwner(), attendanceAndMember -> {
if (attendanceAndMember != null && attendanceAndMember instanceof AttendanceMemberModel) {
clokedInOutMember = attendanceAndMember.member;
}
showResultClockInOutPopup();
});
}
If still it don't work kindly let me know. Thank you.
I writing autotests for application. On the start of application it has an onboarding (ViewPager) with some pages and button on the last page. I need to swipe these pages and press the button. This is my class for onboarding
public class Onboarding {
ViewInteraction onboardingScreen = onView(
allOf(withId(R.id.vp_onboarder_pager),
childAtPosition(
allOf(withId(R.id.cl_onboarder),
childAtPosition(
withId(android.R.id.content),
0)),
0),
isDisplayed()));
ViewInteraction skipButton = onView(allOf(withId(R.id.btn_finish)));
ViewAction skipOnboardingScreen = new ViewAction() {
#Override
public Matcher<View> getConstraints() {
return any(View.class);
}
#Override
public String getDescription() {
return null;
}
#Override
public void perform(UiController uiController, View view) {
ViewPager onboardingPager = (ViewPager) view;
OnboarderAdapter adapter = (OnboarderAdapter) onboardingPager.getAdapter();
int currentPage = 0;
int screenCount = adapter.getCount();
while (screenCount > 0){
onboardingPager.setCurrentItem(currentPage);
screenCount--;
currentPage++;
}
skipButton.perform(click());
}
};
public void skipOnboarding() {
onboardingScreen.perform(skipOnboardingScreen);
}
I call my test in this way:
#Test
public void onboardingPass() {
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
Onboarding onboarding = new Onboarding();
onboarding.skipOnboarding();
}
When test executing, onboardingPager.setCurrentItem(currentPage) must switch current page, but it does not. When I saw it in debuger, test execute this line, but pages does not switching. Why it can be? Thanks.
... I need to swipe these pages ...
To swipe in your instrumentation tests use this with your view;
onboardingScreen.perform(swipeRight());
swipeRight() is from AndroidX Test package androidx.test.espresso.action.ViewActions.swipeRight
Read more about the AndroidX Test Espresso ViewActions package here.
Setup the swipes as per your requirement and see if it helps.
If you're trying to scroll to the last page of your ViewPager, then you should use ViewPagerActions.scrollToLast instead. And I'm sure that they can all be reduced to as simple as:
public void skipOnboarding() {
onView(withId(R.id.vp_onboarder_pager)).perform(ViewPagerActions.scrollToLast());
onView(withId(R.id.btn_finish)).perform(click());
}
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 an issue when I am trying to set text from a last item of a listView into text View which is in the MainActivity. It crashes during running time on “NullPointerException” because I think that that when I’m calling it in MainActivity, It didn’t finish to download on the ListView so when the MainActivity first launched, the listView did not finish his work and the functions getCount(),getItem() and my function getLastElement() are still null.
The issue is that I am not very good with dealing with Thread (Wait(), notify(),..)
Can you please help me with all this?
Here is my code and my LogCat :
public class MainActivity extends Activity implements OnClickListener{
private static Context mContext;
public Button mExit, mHistory, mRating;
public TextView mSignal;
HistoryAdapt myAdapter;
HistoryItems m_myLastItem;
ArrayList<HistoryItems> m_myListItem;
Runnable m_run;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MainActivity.mContext=getApplicationContext();
mExit=(Button)findViewById(R.id.ExitButton);
mExit.setOnClickListener(this);
mHistory=(Button)findViewById(R.id.HistoryButton);
mHistory.setOnClickListener(this);
mRating=(Button)findViewById(R.id.RateButton);
mRating.setOnClickListener(this);
mSignal=(TextView)findViewById(R.id.SignalOfTheDayTV);
//### SET LAST ELEMENT INTO TEXTVIEW
m_myListItem = new ArrayList<HistoryItems>();
myAdapter= new HistoryAdapt(mContext, m_myListItem);
new Thread(
new Runnable(){
#Override
public void run(){
try{
///Need to wait until the data to be downloaded inside HistoryAdapt so it can show the last element from the ListView here
HistoryParser parser = new HistoryParser();
parser.parse(getInputStream(HistoryAct.RSS_LINK));
} catch (XmlPullParserException e) {
Log.w(e.getMessage(), e);
} catch (IOException e) {
Log.w(e.getMessage(), e);
} finally {
//notify that the data finished to download
MainActivity.this.runOnUiThread(
new Runnable(){
public void run(){
m_myLastItem = myAdapter.getLastElement();
//set last signal into TextView
mSignal.setText(m_myLastItem.getTitle());
}
}
);
}
}
}
).run();
//#RATER
// AppRater.app_launched(this);
// AppRater.showRateDialog(this, null);
//Get a Tracker (should auto-report)
((AppManager) getApplication()).getTracker(AppManager.TrackerName.APP_TRACKER);
}//oncreate
private InputStream getInputStream(String link) {
try {
URL url = new URL(link);
return url.openConnection().getInputStream();
} catch (IOException e) {
Log.w(Constants.DATA, "Exception while retrieving the input stream", e);
return null;
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public static Context getAppContext(){
return MainActivity.mContext;
}
public void ExitState(){
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("You're about to quit Signals4Trading");
builder.setIcon(R.drawable.five);
//builder.setMessage("Your device has been registered successfully. You'll receive signals very soon.");
builder.setMessage("Are you sure you want to quit?");
builder.setCancelable(false);//can't click on the background of the activity
builder.setPositiveButton("Yes",new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(),"See you soon", Toast.LENGTH_LONG).show();
finish();
}//OnClickListener PositiveButton
});//anonymous class PositiveButton
builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(),"Enjoy your visit", Toast.LENGTH_LONG).show();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}//ExitState
public void goToHistoryActivity(){
Intent intent = new Intent(MainActivity.this, HistoryAct.class );
startActivity(intent);
}
public void rateApp(){
Intent intent = new Intent(MainActivity.this, Rate.class);
startActivity(intent);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()){
case R.id.ExitButton:
ExitState();
break;
case R.id.HistoryButton:
goToHistoryActivity();
break;
case R.id.RateButton:
rateApp();
break;
}
}
#Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
//Get an Analytics tracker to report app starts & uncaught exceptions etc.
GoogleAnalytics.getInstance(this).reportActivityStart(this);
}
#Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
//Stop the analytics tracking
GoogleAnalytics.getInstance(this).reportActivityStop(this);
}
}//MainActivity
package com.Signals4Trading.push.android;
import java.util.List;
import android.content.Context;
import android.content.Intent;
import android.os.StrictMode;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class HistoryAdapt extends BaseAdapter {
private final List<HistoryItems>items;
private final Context context;
public HistoryAdapt(Context context,List<HistoryItems>items){
this.context=context;
this.items=items;
}//constructor
#Override
public int getCount() {
// TODO Auto-generated method stub
return items.size();
}
#Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return items.get(position);
}
#Override
public long getItemId(int id) {
// TODO Auto-generated method stub
return id;
}
//###FUNCTION THAT RETURN LAST ELEMENT
public HistoryItems getLastElement(){
return items.get(items.size()-1);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ViewHolder holder;
if (convertView == null) {
convertView = View.inflate(context, R.layout.historyitems, null);
holder = new ViewHolder();
holder.itemTitle = (TextView) convertView.findViewById(R.id.itemTitleTV);
holder.itemDate=(TextView) convertView.findViewById(R.id.itemDateTV);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.itemTitle.setText(items.get(position).getTitle());
holder.itemDate.setText(items.get(position).getDate());
}
return convertView;
}
class ViewHolder {
TextView itemTitle;
TextView itemDate;
}
}
//HistoryAdapt
11-13 15:18:34.702: E/AndroidRuntime(7737): FATAL EXCEPTION: main
11-13 15:18:34.702: E/AndroidRuntime(7737): Process: com.Signals4Trading.push.android, PID: 7737
11-13 15:18:34.702: E/AndroidRuntime(7737): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.Signals4Trading.push.android/com.Signals4Trading.push.android.MainActivity}:
java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1
11-13 15:18:34.702: E/AndroidRuntime(7737): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
Your onCreate() call in the Activity is calling:
m_myLastItem= HistoryAdapt.getLastElement();
But, the constructor for HistoryAdapt has not been called yet, and that is where you initialize the static field items within it. I would recommend rethinking this class and its usage as you're using it in an instance manner but have it partially coded as if it is a static class. A good rule of thumb to follow is don't make your static methods dependent on the class being constructed. At that point it's just an instance method.
Looks like you're trying to perform an asynchronous operation using a runnable, then before the asynchronous operation is completed you're trying to use the value it is supposed to set. So I'm assuming you're trying to create a background thread that waits for the data and updates/notifies the UI/UI-thread when it's done loading. This would mean that the asynchronous operation is created and started by the UI-thread during OnCreate and while it is running the UI-thread can happily go on executing the OnCreate method and loading the UI etc.
First of all, it looks like you're creating a runnable but not running it. If you want to run the runnable in a different (asynchronous) thread, try this:
new Thread(
new Runnable()
{
#Override
public void Run()
{
//your code here
}
}
).Run();
*note: Translated this from C#, may not be 100% correct (caps?) but should be really easy to get working.
It's not entirely clear from your code but I assume the code in your runnable fills the HistoryAdapt class with data. Be careful not to create concurrency issues this way. If two threads are trying to access the same object at the same time you may have problems so be sure to properly "lock" objects before using them in seperate threads. In java you can use a "synch" clause to do this:
synchronized(this){
this = newvalue;
}
This makes sure that while the code inside the braces is executing the "this" object cannot be accessed by other threads. Other threads will then wait untill the code is executed and the object is released before continuing.
Secondly, you should be aware that the runnable/thread you've created is basicly a thread that is run once and then disposed (so not a dedicated thread). In this case monitor/wait is not really necessary. You could simply include the code that updates the UI (mSignal.setText(m_myLastItem.getTitle());) in the finally clause of your try/catch statement. Be sure to use the runOnUiThread method when you're trying to update/edit UI-elements from seperate threads like so:
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
m_myLastItem = HistoryAdapt.getLastElement();
//set last signal into TextView
mSignal.setText(m_myLastItem.getTitle());
}
});
This way, the thread is created in OnCreate, does its job seperately from the UI-thread, then updates the UI as soon as it is done. One possible problem you might have is that mSignal.setText() could get called at a moment when the UI isnt ready to be updated, not sure this will really be a problem in this case though. Also, when using this technique in other places you may need a reference to your activity to use inside your thread (you can't always get a reference from the place where you're defining the thread/runnable), that's easy enough, just make a static reference to your activity somewhere in your app and reference that (i prefer an App_Session class for static variables used app-wide).
Hope I understood the question correctly and this helps. In any case, good luck!
*Edit: Full example
new Thread(
new Runnable()
{
#Override
public void run()
{
if(!HistoryAdapt.hasBeenInitiated)
{
try
{
///Need to wait until the data to be downloaded inside HistoryAdapt so it can show the last element from the ListView here
HistoryParser parser = new HistoryParser();
parser.parse(getInputStream(HistoryAct.RSS_LINK));
} catch (XmlPullParserException e) {
Log.w(e.getMessage(), e);
} catch (IOException e) {
Log.w(e.getMessage(), e);
} finally {
//notify that the data finished to download
MainActivity.this.runOnUiThread(
new Runnable()
{
public void run()
{
if (!HistoryAdapt.hasBeenInitiated)
{
m_myLastItem = HistoryAdapt.getLastElement();
//set last signal into TextView
mSignal.setText(m_myLastItem.getTitle());
}
}
}
);
}
}
}
}
).run();
Could not test this unfortunately since i can't run Java (i use xamarin), should be correct though, maybe the #override isnt needed and im not sure if it's supposed to be 'Run' or 'run'. I'm sure you'll figure that out though ;)
Thread run = new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
}
run = new Thread( new Runnable(){
public void run(){
if(!HistoryAdapt.hasBeenInitiated){
try {
///Need to wait until the data to be downloaded inside HistoryAdapt so it can show the last element from the ListView here
HistoryParser parser = new HistoryParser();
parser.parse(getInputStream(HistoryAct.RSS_LINK));
} catch (XmlPullParserException e) {
Log.w(e.getMessage(), e);
} catch (IOException e) {
Log.w(e.getMessage(), e);
}finally{
//notify that the data finished to download
}
}
}
});
run.start();
run.join();
use this but it will wait until your run thread finish.
I have been searching for an answer to my problem, but I seem to get none, despite of how many tutorials I followed, how many questions I've gone through and how many things I've tried to do what I want. Basically, I stumbled upon some good tips, and still couldn't manage to do what wanted.
THE PROBLEM
I am creating an Android Application that will use Fragments (alongside with tabs). In these fragments, I have crucial information relating the application, such as text boxes, and buttons. However, I want to do something really simple, which is updating one of my fragments as I come back to it (imagine I swipe back to a fragment, and I update it with the relevant information). Where is the information stored? On a node.js server, to which I call every time I want information. So for that, I created the following structure.
THE STRUCTURE
First of all, I started off creating my Activity.
public class CentralActivity extends FragmentActivity {
CentralPagerAdapter mCentralActivity;
ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_central);
tabHandler();
}
public void tabHandler() {
mCentralActivity = new CentralPagerAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.CentralPager);
mViewPager.setAdapter(mCentralActivity);
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
getActionBar().setSelectedNavigationItem(position);
}
});
//Action Bar Stuff
}
}
With this said, I need my CentralPagerAdapter, which I created as follows.
public class CentralPagerAdapter extends FragmentStatePagerAdapter {
private int nSwipes = 3;
public CentralPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int i) {
Fragment fragment = new CentralFragment();
Bundle args = new Bundle();
args.putInt(CentralFragment.ARG_OBJECT, i + 1);
fragment.setArguments(args);
return fragment;
}
#Override
public int getCount() {
return nSwipes;
}
}
And now, my fragment, which is only a class that contains all of my views, and options and so on.
public class CentralFragment extends Fragment {
public static final String ARG_OBJECT = "object";
private View rootView;
private RESTFunction currentFunction;
//Has the info I want
private ArrayList<Integer> tickets = new ArrayList<Integer>();
#SuppressLint("HandlerLeak")
private Handler threadConnectionHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (currentFunction) {
case GET_CLIENT_TICKETS:
handleGetTickets(msg);
break;
case BUY_CLIENT_TICKETS:
break;
default:
break;
}
}
};
#Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container,
Bundle savedInstanceState) {
final Bundle args = getArguments();
handleFragments(inflater, container);
getTicketInfo(null);
return rootView;
}
private void handleFragments(LayoutInflater inflater, ViewGroup container) {
Bundle args = getArguments();
if (args.getInt(ARG_OBJECT) == 1) {
rootView = inflater.inflate(R.layout.fragment_show_tickets,
container, false);
showTicketsHandler();
} else if (args.getInt(ARG_OBJECT) == 2) {
rootView = inflater.inflate(R.layout.fragment_buy_tickets,
container, false);
buyTicketsHandler();
} else {
rootView = inflater.inflate(R.layout.fragment_history_tickets,
container, false);
}
}
public void showTicketsHandler() {
//Get stuff from the tickets array that the REST call will handle
//And set them to boxes or radio buttons
}
public void buyTicketsHandler() {
//Get stuff from the tickets array that the REST call will handle
//And set them to boxes or radio buttons
//As well as button click listeners
}
public void getTicketInfo(ProgressDialog progDialog) {
//Connect to the thread to get the information
//In this case, I have no parameters
ConnectionThread dataThread = new ConnectionThread("myLink", Method.GET, null, threadConnectionHandler, progDialog);
dataThread.start();
}
//Get stuff from the resulting JSON and store it in the tickets ArrayList
private void handleGetTickets(Message msg) {
JSONObject ticketListing = (JSONObject) msg.obj;
try {
tickets.add(ticketListing.getInt("t1"));
tickets.add(ticketListing.getInt("t2"));
tickets.add(ticketListing.getInt("t3"));
} catch (JSONException e) {
e.printStackTrace();
}
}
}
And then, I have my thread..
public class ConnectionThread extends Thread {
private ConnectionRunnable runConnection;
private Handler mHandler;
private ProgressDialog progDialog;
public ConnectionThread(String link, Method method, ArrayList<NameValuePair> payload, Handler handler, ProgressDialog progDialog) {
runConnection = new ConnectionRunnable(link, method.toString(), payload);
mHandler = handler;
this.progDialog = progDialog;
}
#Override
public void run() {
runConnection.run();
threadMsg();
if(progDialog != null)
progDialog.dismiss();
}
public JSONObject getJSON() {
return runConnection.getResultObject();
}
private void threadMsg() {
Message msgObj = mHandler.obtainMessage();
msgObj.obj = getJSON();
mHandler.sendMessage(msgObj);
}
}
And ConnectionRunnable is where I run my HttpURLConnection.
SO WHAT DO I NEED?
Basically, what I'm trying to do, is to get the ticket information from the ConnectionThread BEFORE I load all my view and update them. Plus, I want to be able to swipe back and forth, and update my information on the array as I swipe through the screens (if I go to the second screen, the tickets will update, and if I come back to the first, they will re-update). So basically, call the ConnectionThread everytime I swipe around. If that is possible that, is.
WHAT HAVE I TRIED?
I've tried several things already, and all of them didn't actually help..
The usage of ProgressDialogs to stop the UI Thread on the onCreateView method of the fragment (no use, because it returns the rootView before it handles everything);
Making the UI Thread sleep for 1 second (I don't know why, it blocks all of them);
Overriding the instantiateMethod() of the Adapter, although I think I didn't do it correctly;
Overriding the saveState() of the Adapter, in order to prevent its saved states, and to then get new ticket information;
Giving the fragments tags to update their rootViews on the Adapter, but to no avail;
Getting the information in the activity, and everytime I make a purchase (second fragment), restart the whole activity to get the tickets, which I believe is a really, really bad solution.
I've read several articles, and I still couldn't find my answers.. It's really frustrating. Because it's something so simple, however, the fact that I have to run the HTTP calls on a different thread delays the whole UI updating process.
I've also read the AsyncTask's method. However, I feel like both Threads and AsyncTasks end up in the same.
WHAT TO DO NOW?
Well, that's what I was hoping to find. Because it ends up being annoying as it is.
POSSIBLE REASONS
Is it because I'm separating all classes into spread files, therefore making my work difficult?
Thank you for your time, guys, hope we can find a solution or something.
THE EDIT
So basically, after 4 hours of reading documents and tutorials, I figured that what I needed was setOffscreenPageLimit(int). However, it can't be set to 0, so I will have to do with a setOnPageChangeListener. Now, to figure how to refresh the fragment, and I'll be as good as new.
Alright, it works perfectly! Basically, I did this:
mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
((CentralFragment)((CentralPagerAdapter) mViewPager.getAdapter()).instantiateItem(mViewPager, position)).refresh();
getActionBar().setSelectedNavigationItem(position);
}
});
Where my .refresh is:
public void refresh() {
Bundle args = getArguments();
if (args.getInt(ARG_OBJECT) == 0) {
getTicketInfo(0);
} else if (args.getInt(ARG_OBJECT) == 1) {
getTicketInfo(1);
buyTicketsHandler();
} else {
//To Handle Later
}
}
It's as simple as refreshing the page before you go to it. Why didn't I remember this before..? So, here's the reference for those who ever need this!