title: How can I serialize my User class for the Firebase Database and fix this error?
body: <p>I'm trying to retrieve the updated User from the dataSnapshot of the Firebase Database: </p>
  
  <pre><code>mRef.addValueEventListener(new ValueEventListener() {
          @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
              User atualizedUser = dataSnapshot.getValue(User.class);
              fName.setText(atualizedUser.getFirstName());
              lName.setText(atualizedUser.getLastName());
              profilePhoto.setProfileId(atualizedUser.getProfileId());
          }
  
          @Override
          public void onCancelled(DatabaseError databaseError) {
  
          }
      });
  }
  </code></pre>
  
  <p>But I get this error below:</p>
  
  <pre><code>com.google.firebase.database.DatabaseException: Class bqs.bomqueso.Model.User is missing a constructor with no arguments
                                                              at com.google.android.gms.internal.zzbtg$zza.zze(Unknown Source)
                                                              at com.google.android.gms.internal.zzbtg$zza.zzaH(Unknown Source)
                                                              at com.google.android.gms.internal.zzbtg.zze(Unknown Source)
                                                              at com.google.android.gms.internal.zzbtg.zzb(Unknown Source)
                                                              at com.google.android.gms.internal.zzbtg.zza(Unknown Source)
                                                              at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
                                                              at bqs.bomqueso.Activities.MainActivity$3.onDataChange(MainActivity.java:92)
                                                              at com.google.android.gms.internal.zzbpx.zza(Unknown Source)
                                                              at com.google.android.gms.internal.zzbqx.zzZS(Unknown Source)
                                                              at com.google.android.gms.internal.zzbra$1.run(Unknown Source)
                                                              at android.os.Handler.handleCallback(Handler.java:746)
                                                              at android.os.Handler.dispatchMessage(Handler.java:95)
                                                              at android.os.Looper.loop(Looper.java:148)
                                                              at android.app.ActivityThread.main(ActivityThread.java:5443)
                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                              at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
                                                              at     com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
  </code></pre>
  
  <p>Here my User class (this is not a subclass, I created it in a separate file):</p>
  
  <pre><code>public class User {
  
  private String firstName;
  private String lastName;
  private String profileId;
  
  public User() { }
  
      public User(String fName, String lName, String id) {
          this.firstName = fName;
          this.lastName = lName;
          this.profileId = id;
      }
  
      public String getProfileId() {
          return profileId;
      }
  
      public void setProfileId(String id) { 
          this.profileId = id; 
      }
  
      public String getLastName() {
          return lastName;
      }
  
      public void setLastName(String lName) { 
          this.lastName = lName; 
      }
  
      public String getFirstName() {
          return firstName;
      }
  
      public void setFirstName(String fName) { 
          this.firstName = fName; 
      }
  }
  </code></pre>
  
  <p>I find similar questions here, but I hadn't found a solution for my problem, I hope you guys can help me, Thank you in advance!</p>