Flutter学习（一）

1.Dart环境安装

官网：Get the Dart SDK | Dart

Mac环境：

Install Homebrew if needed. https://brew.sh/

Add the official tap.

  $ brew tap dart-lang/dart

Install the Dart SDK.

  $ brew install dart

2.vscode配置

安装dart插件

安装code runner 插件

3.dart语法(一)：

print('你好，dart');

  //脚本类语言，可以不预先定义类型，自动类型辨别
  var str = "this is  var";
  String str1 = "this is var";
  int str2 = 123;

  //常量  值不变，开始就要初始化
  const var str3 = "var" ;
  //常量 可以开始不赋值，只能赋值一次
  final var str4 = DateTime.now();

  //常用数据类型
  bool flag = true;
  int num1 = 1;
  double num2 = 1.1;
  String str5 = "str5";

  var list = ["str","str1",123,true];
  print(list.length);
  print(ist[0]);

  var list1 = <String>["str","str1","str2"];

  var list2 = [];
  list2.add("str1");

  var list3 = List.filled(2, ""); //固定长度 2 
  list3[0] = "str";

  var list4 = List<String>.filled[2,""];

  var person = {
    "age":18,
    "sex":"男",
    "work":["程序员","滴滴"]
  } 
  var sex = person["sex"];

  var p = new Map();
  p["name"] = "王哥";

  //判断类型 is
  var str45 = "1234";
  if(str45 is String) {
    print("yes");
  }else if(str45 is int) {
    print("no");
  }else {
    print("no");
  }