1. // import 'package:operation/operation.dart' as operation;
    3. main(List<String> arguments) {
    5.   toInt();
    7.   Person p = Person();
    9.   // 级联
    10.   p..name = 'wang'
    11.    ..country = 'USA'
    12.    ..setCountry('CHINA');
    14.   print(p);
    16.   // if 语句
    17.   int i = -2;
    18.   if (i < 0) {
    19.     print('i < 0');
    20.   }else if (i == 0) {
    21.     print('i == 0');
    22.   }else {
    23.     print('i > 0');
    24.   }
    26.   // 循环
    27.   for (int i = 0; i < 3; i++) {
    28.     print(i);
    29.   }
    30.   print('------------------------');
    31.   var collection = [1, 2, 3];
    32.   collection.forEach((x) => print(x)); // forEach的参数为Function
    33.   print('------------------------');
    34.   for(var x in collection) {
    35.     print(x);
    36.   }
    38.   // switch的参数可以是num, 或者String
    39.   var command = 'OPEN';
    40.   switch (command) {
    41.     case 'OPEN':
    42.       print('OPEN');
    43.       break;
    44.     case 'CLOSE':
    45.       print('CLOSE');
    46.       break;
    47.     default:
    48.       print('DEFAULT');
    49.   }
    51.   // 异常处理
    52.   try {
    53.     throw 'this is a Exception';
    54.   } on Exception catch (e) {
    55.     print('unknown exception: $e');
    56.   } catch (e) {
    57.     print('unknown type: $e');
    58.   }finally {
    59.     print('close');
    60.   }
    61. }
    63. toInt() {
    65.   int a = 3;
    66.   int b = 2;
    67.   // 取整
    68.   print(a~/b);
    69. }
    71. class Person {
    73.   String name;
    74.   String country;
    76.   void setCountry(String country) {
    77.     this.country = country;
    78.   }
    80.   String toString() => 'Name: $name\nCountry: $country';
    82. }