java - How to change data in dynamically added Android Views at runtime -


i have , android app adds tableviews, tablerows , textviews dynamically @ run time according data found in firebase repository. more specifically, tableview added each "poll" found in repo static linearlayout, each "election" found in poll tablerow added tablelayout, , each "nominee" in election tablerow containing 2 textviews data added tablelayout well. potentially have multiple tables added @ runtime, each containing rows multiple elections, , each election having multiple data rows nominees. here's static layout measure....

     <?xml version="1.0"?>     <scrollview android:layout_height="android:layout_width="match_parent" android:id="@+id/scrollview1" xmlns:android="http://schemas.android.com/apk/res/android">  <linearlayout android:layout_height="match_parent" android:layout_width="match_parent" android:id="@+id/linearlayout" android:orientation="vertical">  </linearlayout>      </scrollview>

..and here's representation of firebase repo...

-polls     numpolls - 5     (pollskey) - name - poll1             numelections - 2             elections                  (electionskey) - name - election1                         numnominations - 2                         numvoters - 2                         numbertoelect - 1                         voters - (votesrkey) - name - charles                                          number - (678) 333-4444                                  .                                  .                                  .                                  (voterskey) - ...                         nominations - (nominationskey) - name - richard nixon                                               numberofvotes - 2                                        .                                        .                                        .                                       (nominationskey) - ...             .             .             .             (electionskey) - ...      .      .      .      (pollskey) - ...

so question has 2 threads. first android oriented...

  1. what's best way iterate through android views added dynamically change textview data when data in repo changes, being case have no idea how many such tableview, or tablerows there @ compile time?

right i'm doing this, it's slow going feel there has better way...

private void appendcandidatesandvotes(datasnapshot election, tablelayout tbl) {         random randgen = new random();         datasnapshot nominees = election.child("nominations");         (datasnapshot nominee : nominees.getchildren()) {              // create row candidate name , number of votes             tablerow rownameandvotes = new tablerow(this);             // generating random row id here allows pass              // valueeventlistener , locate row in              // case of data change (someone has cast vote)              // can update             int uniquerowid = randgen.nextint(1000);             rownameandvotes.setid(uniquerowid);             rownameandvotes.setbackgroundcolor(color.white);             rownameandvotes.setlayoutparams(new tablerow.layoutparams (                     layoutparams.match_parent,                     layoutparams.wrap_content));              // create candidate name view             textview viewcandidatename = new textview(this);             viewcandidatename.setid(2);             viewcandidatename.settext(nominee.child("name").getvalue(string.class));             viewcandidatename.settextcolor(color.black);             viewcandidatename.setpadding(5,  5,  5, 5);             rownameandvotes.addview(viewcandidatename);              // create number of votes view             textview viewnumvotes = new textview(this);             viewnumvotes.setid(3);             viewnumvotes.settext(nominee.child("numberofvotes").getvalue(string.class));             viewnumvotes.settextcolor(color.black);             viewnumvotes.setpadding(3,  5,  5,  5);             rownameandvotes.addview(viewnumvotes);              // add row table             tbl.addview(rownameandvotes);              // lets firebase reference nominee ,             // attach listener alert future changes of             // values therein, can update vote counts dynamically             firebase nomineeref = nominee.getref();             nomineeref.addvalueeventlistener(new valueeventlistener() {                  @override                 public void ondatachange(datasnapshot nomineesnapshot) {                      string nomineename = nomineesnapshot.child("name").getvalue(string.class);                     linearlayout layout = (linearlayout) findviewbyid(r.id.linearlayout);                     int layoutchildcount = layout.getchildcount();                     (int = 0; < layoutchildcount; i++) {                         view layoutchildview = layout.getchildat(i);                         // if table, loop through row                         if (layoutchildview instanceof tablelayout) {                             tablelayout tbl = (tablelayout)layoutchildview;                             int tablechildcount = tbl.getchildcount();                             (int j = 0; j < tablechildcount; j++) {                                 view tblchildview = tbl.getchildat(i);                                 if (tblchildview instanceof tablerow) {                                     tablerow row = (tablerow)tblchildview;                                     int rowchildren = row.getchildcount();                                     (int k = 0; k < rowchildren; k++) {                                         textview tv = (textview)(row.getchildat(k));                                         string rowcandidatename = tv.gettext().tostring();                                         if (rowcandidatename) ...                                     }                                 }                             }                         }                     }                 }

i think way layed out, layout can directly refer base linearlayout. can give tablerows unique ids setid(), far know can't pass data valueeventlistener, nor can refer variables in enclosing scope (i hope i'm wrong this, make things way easier). know can refer static final variables inside valueeventlistener, don't see how me since don't know how many tables or rows i'll dealing @ runtime.

so, in short, how can link particular call valueeventlistener tablerow it's data associated with?

now question 2, bit more firebase specific....

  1. it seems valueeventlistener called once when activity loaded, , again changes underlying data. want called changes underlying data, not on loading. using wrong eventlistener? or there way avoid behavior?

for firebase specific question - design. firebase doesn't encourage distinguishing between initial data , data updates, since in real-time scenario can never "caught up" latest data.

if don't want retrieve data on startup, i'd use queries , limits restrict data can receive. instance, if want receive latest 100 polls, like:

firebase ref = new firebase(url); query q = ref.limit(100); q.addchildeventlistener(...);

and child event listener called once per poll. when new poll added called again (and there child-removed event oldest poll in list of 100).

hope helps!


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