如何在Dart创建私有变量? [英] How in Dart create private variable?
问题描述
我想创建私有变量,但我不能。
I want create private variable but I cannot.
这里是我的代码:
void main() {
var b = new B();
b.testB();
}
class A {
int _private = 0;
testA() {
print('int value: $_private');
_private = 5;
}
}
class B extends A {
String _private;
testB() {
_private = 'Hello';
print('Srting value: $_private');
testA();
print('Srting value: $_private');
}
}
当我运行此代码时,得到以下结果:
When I run this code, I get the following result:
Srting value: Hello
int value: Hello
Breaking on exception: type 'int' is not a subtype of type 'String' of 'value'.
编辑此源代码时也不会出现任何错误或警告。
Also I not get any error or warnings when editing this source code.
如何在Dart中创建私有变量?
How I can create private variable in Dart?
推荐答案
From Dart documentation:
与Java不同,Dart没有public,protected和private关键字。如果标识符以下划线
_
开头,则对其库而言是私有的。
Unlike Java, Dart doesn’t have the keywords public, protected, and private. If an identifier starts with an underscore
_
, it’s private to its library.
库不仅提供API,而且是隐私单位:以下划线 _
开头的标识符只能在库中显示。
Libraries not only provide APIs, but are a unit of privacy: identifiers that start with an underscore _
are visible only inside the library.
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