Dart 语言

https://dart.ranyunlong.com/

https://github.com/dart-lang/dartdoc

http://web.mit.edu/dart-lang_v1.24.2/gen-dartdocs/index.html

https://book.flutterchina.club/

国外安卓开发者博客

https://dart.ranyunlong.com/guide/handbook/functions.html#%E5%91%BD%E5%90%8D%E5%8F%AF%E9%80%89%E5%8F%82%E6%95%B0

对象操作符：
? 条件运算符
as 类型转换，强转
is 类型判断
.. 级联操作（连缀）

void main(List<String> args) {
  SomaTempVO soma = SomaTempVO.build(12.1, 56);
  // 判断类型
  print(soma is SomaTempVO);
  // 强转为Object类型
  (soma as Object).toString();
  // 级联操作
  soma
    ..hum = 60
    ..temp = 5
    ..updateTime = DateTime.parse("2020-01-16");
  print(soma.toJson());
  //如果对象为空，则不会运行这句
  soma = null;
  soma?.printPublic();
}