hint at AppCompatAutoCompleteTextView is not set properly from java

Question

I want to dynamically set the hint of an AppCompatAutoCompleteTextView from the java code, and moving on top when writing like at the following image:

The issue is that when I am setting the from the xml (static) everything works fine:

                    <androidx.appcompat.widget.AppCompatAutoCompleteTextView
                        android:id="@+id/myid"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:hint="Username"
                        android:imeOptions="actionDone"
                        android:singleLine="true" />

but when I remove the hint from the xml and add it from the java code:

final AutoCompleteTextView companyAutocomplete = findViewById(R.id.myid);
companyAutocomplete.setHint("new hint");

the hint is not moving on top when start writing.

Could you help me understand what i am missing? Thanks