la base de données.DatabaseException: impossible de convertir un objet de type java.lang.Chaîne de type

Mon Problème

      08-10 04:23:28.820 21501-21501/my.org.medicare.medicareapp E/AndroidRuntime: FATAL EXCEPTION: main                                              Process: my.org.medicare.medicareapp, PID: 21501                                             com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type my.org.medicare.medicareapp.protest
at com.google.android.gms.internal.zzaln.zzd(Unknown Source)
at com.google.android.gms.internal.zzaln.zzb(Unknown Source)
at com.google.android.gms.internal.zzaln.zza(Unknown Source)
at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
at my.org.medicare.medicareapp.FirebaseHelper.fetchData(FirebaseHelper.java:50)
at my.org.medicare.medicareapp.FirebaseHelper.access$000(FirebaseHelper.java:14)            atmy.org.medicare.medicareapp.FirebaseHelper$1.onChildAdded(FirebaseHelper.java60)at com.google.android.gms.internal.zzahe.zza(Unknown Source)                                      at com.google.android.gms.internal.zzaje.zzcta(Unknown Source)                          at com.google.android.gms.internal.zzajh$1.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Mon Activité Principale Code:

 rv = (RecyclerView) findViewById(R.id.rv);
        rv.setLayoutManager(new LinearLayoutManager(this));
        //INITIALIZE FIREBASE DB
        db = FirebaseDatabase.getInstance().getReference().child("Pro");;

        helper = new FirebaseHelper(db);
        //ADAPTER
        adapter = new MyAdapter(this, helper.retrieve());
        rv.setAdapter(adapter);

Et mon FirebaseHelper:

public class FirebaseHelper {
DatabaseReference db;
Boolean saved=null;
ArrayList<protest> spacecrafts=new ArrayList<>();
public FirebaseHelper(DatabaseReference db) {
this.db = db;
}
//WRITE IF NOT NULL
public Boolean save(protest spacecraft)
{
if(spacecraft==null)
{
saved=false;
}else
{
try
{
db.child("Pro").push().setValue(spacecraft);
saved=true;
}catch (DatabaseException e)
{
e.printStackTrace();
saved=false;
}
}
return saved;
}
//IMPLEMENT FETCH DATA AND FILL ARRAYLIST
private void fetchData(DataSnapshot dataSnapshot)
{
spacecrafts.clear();
//dataSnapshot.getChildren()
for (DataSnapshot ds : dataSnapshot.getChildren())
{
protest spacecraft=ds.getValue(protest.class);
spacecrafts.add(spacecraft);
}
}
//READ THEN RETURN ARRAYLIST
public ArrayList<protest> retrieve() {
db.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
fetchData(dataSnapshot);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
fetchData(dataSnapshot);
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
return spacecrafts;
}
}

Mon point de vue Titulaire

public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView nameTxt,propTxt,descTxt;
ItemClickListener itemClickListener;
public MyViewHolder(View itemView) {
super(itemView);
nameTxt= (TextView) itemView.findViewById(R.id.nameTxt);
propTxt= (TextView) itemView.findViewById(R.id.propellantTxt);
descTxt= (TextView) itemView.findViewById(R.id.descTxt);
itemView.setOnClickListener(this);
}
public void setItemClickListener(ItemClickListener itemClickListener)
{
this.itemClickListener=itemClickListener;
}
@Override
public void onClick(View view) {
this.itemClickListener.onItemClick(this.getLayoutPosition());
}

Ci-dessous est ma structure de données, j'essaie de lire "Pro"

Structure De Données

Ma Protestation structure:

public class protest {
private String name;
private String contact;
private String centre;
public protest(){};
public String getName(){return name;}
public String getContact(){return contact;}
public String getCentre(){return centre;}
public void setName(String name) {
this.name = name;
}
public void setContact(String contact) {
this.contact = contact;
}
public void setCentre(String centre) {
this.centre = centre;
}
}

Pourrais-je savoir quel est le problème? Je suis nouveau sur firebase et j'ai besoin de votre aide. J'ai lu quelques question similaire ici, mais je n'arrive toujours pas à résoudre mon problème. Peut-expert ici m'aider?

Mise à jour:
Testé à nouveau avec impression..
lorsque Datasnapshot aller à

  public ArrayList<protest> retrieve() {
db.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
System.out.println(dataSnapshot.getValue());
fetchData(dataSnapshot);
}

08-10 06:26:47.548 26700-26700/ma.org.l'assurance-maladie.medicareapp j'/Système.: {nom=lee, contact=123456, centre=jalan ipoh}

Mais quand Datasnapshot aller à

 private void fetchData(DataSnapshot dataSnapshot)
{
spacecrafts.clear();
//dataSnapshot.getChildren()
for (DataSnapshot ds : dataSnapshot.getChildren())
{
System.out.println(ds.getValue());
protest spacecraft=ds.getValue(protest.class);
spacecrafts.add(spacecraft);
}
}

08-10 06:26:47.548 26700-26700/ma.org.l'assurance-maladie.medicareapp j'/Système.: jalan ipoh

Quel est le problème?

OriginalL'auteur jeff | 2016-08-10