匿名内部类中的变量和访问

Question

I have some question about anonymous inner-class. I just realize that in my anonymous inner-class can refer to two variable with the same name to outter class and in ineer-class it self, How do I know that what it refer to at that moment.

This is my code.

public class RealmUpdate {

private Realm realm;
public void upsertUserProfile( final String email, final String fname, final String lname,
                               final String gender, final String birthdate, final String tel){
    realm.executeTransactionAsync(new Realm.Transaction() {
        @Override
        public void execute(@NonNull Realm realm){
            try{
                realm = Realm.getDefaultInstance();
                SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
                String[] arr_date = birthdate.split("/");
                String real_date = arr_date[2] + "-" + arr_date[1] + "-" + arr_date[0];
                Log.d( getClass().getSimpleName(), real_date);
                Date date = format.parse(real_date);
                UserProfile data = realm.where(UserProfile.class)
                        .equalTo("Email", email)
                        .findFirst();
                if( data == null){
                    Log.d(RealmUpdate.class.getSimpleName(), "No account in DB.");
                    UserProfile userProfile = realm.createObject(UserProfile.class, email);
                    Log.d( getClass().getSimpleName(), "Value add: Start!?");
                    userProfile.setFName(fname);
                    Log.d( getClass().getSimpleName(), "Value add: fName!?");
                    userProfile.setLName(lname);
                    Log.d( getClass().getSimpleName(), "Value add: lName!?");
                    userProfile.setGender(gender);
                    userProfile.setBirthdate(date);
                    userProfile.setTel(tel);
                    Log.d( getClass().getSimpleName(), "Value add!?");
                    realm.close();
                    return;
                }
                Log.d(RealmUpdate.class.getSimpleName(), "Found account in DB");
                data.setEmail(email);
                data.setFName(fname);
                data.setLName(lname);
                data.setGender(gender);
                data.setBirthdate(date);
                data.setTel(tel);
                realm.close();
            } catch(ParseException exception) {
                realm.close();
                exception.printStackTrace();
                Log.e( getClass().getSimpleName(), "Catch Error!!!");
            }
        }
    }, new Realm.Transaction.OnSuccess() {
        @Override
        public void onSuccess() {
            Log.d( getClass().getSimpleName(), "Add profile success");
        }
    }, new Realm.Transaction.OnError() {
        @Override
        public void onError(Throwable error) {
            realm.close();
            Log.d( getClass().getSimpleName(), "Add profile not success");
        }
    });
    realm.close();
}

From my code, I have 2 Realm object that name "realm" the first is declare in main class and others one is declare in anonymous inner-class. When I try to change the name Realm object of main class to

private Realm realm_test;

it only show the error at

realm.executeTransactionAsync(new Realm.Transaction() {

, the code in anonymous inner-class still fine. But when I change the name of variable in anonymous inner class like this,

 public void execute(@NonNull Realm realm_test_inner){

the code in anonymous inner-class got no error too.

Now, I'm very confuse with these because it cause the error when I insert data to database(can fixed it now), but I'm still not sure what does it really happen?

Answer 1

This feature is named shadowing. You can read about it here:

https://docs.oracle.com/javase/tutorial/java/javaOO/nested.htm