问从Firebase迭代dataSnapshot.value哈希映射的值

EN

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference mototrackRef = rootRef.child("mototrack");
    mototrackRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            for (DataSnapshot ds : task.getResult().getChildren()) {
                String motoBrand = ds.child("motoBrand").getValue(String.class);
                Log.d("TAG", motoBrand);
            }
        } else {
            Log.d("TAG", task.getException().getMessage()); //Don't ignore potential errors!
        }
    }
});

val rootRef = FirebaseDatabase.getInstance().reference
val mototrackRef = rootRef.child("mototrack")
mototrackRef.get().addOnCompleteListener { task ->
    if (task.isSuccessful) {
        for (ds in task.result.getChildren()) {
            val motoBrand = ds.child("motoBrand").getValue(String::class.java)
            Log.d("TAG", motoBrand)
        }
    } else {
        Log.d("TAG", task.exception.getMessage()) //Don't ignore potential errors!
    }
}