泛型

实现缓存类

// 泛型
void main(){
  Cache c = Cache();
  c.setItem('config01', 11);
  c.setItem('config02', 'chanchaw');
  print(c.toString());

}

class Cache<T> {
  final Map<String, T> _cached = {};
  void setItem(String key,T value){
    _cached[key] = value;
  }
  T? getItem(String key){
    return _cached[key];
  }

  @override
  String toString(){
    String ret = '';
    _cached.forEach((key,value) => ret = ret + '$key:${value.toString()}\n');
    return ret;
  }
}