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Dart Libraries and visibility

Unlike Java, Dart doesn’t have the keywords public, protected, and private. If an identifier startswith an underscore _, it’s private to its library.

If you for example have class A in a separate library file (eg, other.dart), such as:

library other;
class A {
 int _private = 0;
 testA() {
 print('int value: $_private'); // 0
 _private = 5;
 print('int value: $_private'); // 5

and then import it into your main app, such as:

import 'other.dart';
void main() {
 var b = new B();
class B extends A {
 String _private;
 testB() {
 _private = 'Hello';
 print('String value: $_private'); // Hello
 print('String value: $_private'); // Hello

You get the expected output:

String value: Hello
int value: 0
int value: 5
String value: Hello


In this page (written and validated by ) you learned about Dart Libraries and visibility . What's Next? If you are interested in completing Dart tutorial, your next topic will be learning about: Dart Specifying a library prefix.

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