如何获取Android Java中onSuccess方法外的值？

Question

I need to get the userRole outside the onSuccess method in Android Java. How to get that? I tried implementing interface and callback function and that also not worked.

 documentReference = firebaseFirestore.collection( "Users").document(firebaseAuth.getCurrentUser().getUid()); documentReference.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() { @Override public void onSuccess(DocumentSnapshot documentSnapshot) { userRole = documentSnapshot.getString("userRole"); } });

Answer 1

There are two options you can use. The first one is using Mutablelivedata and the second is using an Interface. Assuming you are using MVVM pattern.

public Mutablelivedata<String> getuserRole(){
  documentReference = firebaseFirestore.collection("Users").document(firebaseAuth.getCurrentUser().getUid());
  documentReference.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
  @Override
  public void onSuccess(DocumentSnapshot documentSnapshot) {
      userRole.setValue(documentSnapshot.getString("userRole"));
    }
 });
return userRole;
}

then in your activity/fragment

yourViewModel.getuserRole.observe(getViewLifecycleOwner(), new new Observer<String>(){
@Overrride
public void onChanged(String s){
//Log.d(TAG, "onChanged: your user role: "+s);
  }
});

The second is making an interface callback

public interface UserRoleInterface(){
  void userRole(String role);
}

Then set the interface as a parameter on your method/function

public void userRole(UserRoleInterface userRoleInterface){
 documentReference = firebaseFirestore.collection("Users").document(firebaseAuth.getCurrentUser().getUid());
 documentReference.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
  @Override
  public void onSuccess(DocumentSnapshot documentSnapshot) {
  userRoleInterface.userRole(documentSnapshot.getString("userRole"));
 }
});

Then in your Activity/Fragment

yourViewModel.userRole(new UserRoleInterface(){
@Override
public void userRole(String role){
//Log.d(TAG, "onChanged: your user role: "+role);
}
});