dart基础---->单例singleton
At least, there are three ways to create the singleton object with dart.
1. factory constructor
class SingletonOne {
SingletonOne._privateConstructor();
static final SingletonOne _instance = SingletonOne._privateConstructor();
factory SingletonOne() {
return _instance;
}
}
2. static field with getter
class SingletonTwo {
SingletonTwo._privateConstructor();
static final SingletonTwo _instance = SingletonTwo._privateConstructor();
static SingletonTwo get instance => _instance;
}
3. static field
class SingletonThree {
SingletonThree._privateConstructor();
static final SingletonThree instance = SingletonThree._privateConstructor();
}
How to instanstiate
The above singletons are instantiated like this:
SingletonOne one = SingletonOne();
SingletonTwo two = SingletonTwo.instance;
SingletonThree three = SingletonThree.instance;
Example to test it
main(List<String> args) {
var s1 = SingletonOne();
var s2 = SingletonOne();
print(identical(s1, s2)); // true
print(s1 == s2); // true
}
作者:
huhx
出处: www.cnblogs.com/huhx
格言:你尽力了,才有资格说自己的运气不好。
版权:本文版权归作者huhx和博客园共有,欢迎转载。未经作者同意必须保留此段声明,且在文章页面明显位置给出原文链接,否则保留追究法律责任的权利。
出处: www.cnblogs.com/huhx
格言:你尽力了,才有资格说自己的运气不好。
版权:本文版权归作者huhx和博客园共有,欢迎转载。未经作者同意必须保留此段声明,且在文章页面明显位置给出原文链接,否则保留追究法律责任的权利。