database - ArrayList loses elements after onChildAdded (Android Studio & Firebase) - 


public void readuniversity(){     childeventlistener unilistener = new childeventlistener() {         @override         public void onchildadded(datasnapshot datasnapshot, string s) {             //log.d(log_tag, datasnapshot.getkey());             university uni = datasnapshot.getvalue(university.class);             universitieslist.add(uni); //adding arraylist of type university             //log.d(log_tag, universitieslist.size()+"is size");             arrayofuniversities.add(uni.getname()); //adding name of university list             //log.d(log_tag, adapter.getcount() + " items");             //log.d(log_tag, arrayofuniversities.size()+" size");             adapter.notifydatasetchanged();         }          @override         public void onchildchanged(datasnapshot datasnapshot, string s) {          }          @override         public void onchildremoved(datasnapshot datasnapshot) {          }          @override         public void onchildmoved(datasnapshot datasnapshot, string s) {          }          @override         public void oncancelled(databaseerror databaseerror) {          }     };      databasereference unireference = database.getreference("note-retrieve/universities");     unireference.addchildeventlistener(unilistener); }

the code pretty self explanatory. using arrayofuniversities list populate spinner need adapter. populating spinner names of universities

i storing university objects in universitieslist

the problem have when leave readuniversity() method lose every element in universitieslist , arrayofuniversities though spinner populated these.

its strange list should have objects stored.

also, have adapter @ top of code in oncreate().

try way. hope work .. :) 

private arrylist<university > universitylist = new arrylist<>(); private arrylist<string> universitysname = new arrylist<>();   mdatabase.getreference().child("path")             .addchildeventlistener(new childeventlistener() {     @override     public void onchildadded(datasnapshot datasnapshot, string s) {         if (datasnapshot != null) {             university muniversity  = datasnapshot.getvalue(university                                          .class);             universitylist.add(muniversity);             universitysname.add(muniversity.getname);          }     }      @override     public void onchildchanged(datasnapshot datasnapshot, string s) {     }      @override     public void onchildremoved(datasnapshot datasnapshot) {      }      @override     public void onchildmoved(datasnapshot datasnapshot, string s) {      }      @override     public void oncancelled(databaseerror databaseerror) {      } });

Comments

Post a Comment

Popular posts from this blog

What is happening when Matlab is starting a "parallel pool"? -

running parallel cpu processes in matlab starts command parpool() according documentation , function: [creates] special job on pool of workers, , [connects] matlab client parallel pool. this function takes bit of time execute, on order of 30 seconds. in other multi-cpu paradigms openmp, parallel execution seems totally transparent -- i've never noticed behavior analogous matlab (granted i'm not experienced parallel programming). so, happening between time parpool() called , when finishes executing? takes long? parallel computing toolbox enables run matlab code in parallel using several different paradigms (e.g. jobs , tasks, parfor , spmd , parfeval , batch processing), , run either locally (parallelised across cores in local machine) or remotely (parallelised across machines in cluster - either 1 own, or 1 in cloud). in of these cases, code run on matlab workers , copies of matlab without interactive desktop. if you're intending run on remo...
Read more

angular - DownloadURL return null in below code -

when change file updated in firebase storage when try downloadurl show null. filechange(event: any) { const imagefolder: string = this.employee.id; const filelist: filelist = event.target.files; const file: file = filelist[0]; const storageref = firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file); console.log(storageref.snapshot.downloadurl); } the put() asynchronous. if want url after file uploaded have this: firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file).then((snapshot) => { storageref = snapshot.downloadurl: console.log(snapshot.downloadurl); });
Read more

php - Cannot override Laravel Spark authentication with own implementation -

during login process of laravel spark need request token of remote api. api stores exact same users , passwords laravel spark application. therefore need username , non hashed password of user during authentication process. i thought overriding authenticated method solution problem. in routes/web.php override post /login endpoint , pointing endpoint own logincontroller: <?php namespace app\http\controllers\auth; use illuminate\support\facades\log; use illuminate\http\request; use laravel\spark\http\controllers\auth\logincontroller sparklogincontroller; class logincontroller extends sparklogincontroller { /** * create new login controller instance. * * @return void */ public function __construct() { parent::__construct(); } /** * handle successful authentication attempt. * * @param request $request * @param \illuminate\contracts\auth\authenticatable $user * @return response */ public fu...
Read more