Dart语法记录

import 'dart:math';

void main() {
  print(initSome());
}

initSome() {
  var name = "hi";
  var age = 18;
  var hight = 1.70;
  dynamic value = 18;
  value = "1";
  Object temp = "1";
  print("$value");
  print(value == temp);
  var temp1;
  print(temp1);
  Person p = Person("ada");
  p.name = "112";
  print("${p.name}");
  String str2 = """Hi,Bruce
  12323
  ooo
  This is Xiaoming.
  """;
  var a = true;
  var arr = ["1", "2", "3"];
  var maps = {
    "1": "1s",
    "2": "1s",
    "3": 1,
  };
  print(arr[1]);
  print(maps["2"]);
  print(maps.length);
  print("\u{1f600}");
  Runes input = new Runes("\u{1f600} \u{1f600} \u{1f600}");
  print(String.fromCharCodes(input));
  shoDesc("Bruce", (name) {
    print("name = $name");
  });
  showDesc1("ada");
  Wrold wrold = Wrold(name);
  var names = wrold?.name; //先判断p是否为null，如果是，则name为null；如果否，则返回p.name值
  print(names);

  var num = 10;
  var resutlt = num ~/ 3; //得出一个小于等于(num/3)的最大整数
  print(resutlt);
  var name1;
  var name2 = name1 ?? "123"; //如果name1不为null，则name2值为name1的值，否则值为123
  print(name2);
  Banane(20, "red") //..的使用，级联操作
    ..showWeight()
    ..showColor();
  /**
   * if and else
      for循环
      while和do-while循环
      break和continue
      switch-case语句
   */
  if (num == 10) {
    print("1");
  } else {
    print("0");
  }
  for (var i = 0; i < 10; i++) {
    print(i);
  }
  try {
    testException();
  } catch (e) {
    print(e);
  }
  //类
  Tree t = Tree.init();
  Tree t1 = new Tree("test111");
  print(t.desc);
  print(t1.desc);
  Apple();
  Apple.desc("say hello");

  Apple1 atemp = Apple1();
  atemp.log(); ////可执行从LogUtil继承过来的方法
  //===================
  //泛型
  FruitFactory<Banana> f = FruitFactory();
  Banana ab = f.produceFutit(Banana("a banana"));
  ab.log();
  FruitFactory<Bjc> f1 = FruitFactory();
  Bjc abc = f1.produceFutit(Bjc("a bjc"));
  abc.log();
  return "1";
}

void shoDesc(var name, Function age) {
  age(name);
}

class Person {
  static const desc = "23";

  var name;

  Person(this.name);
}

String getname() {
  return "1";
}

void showDesc1(var name) {
  print("that is a nested function!");
  void println(var name) {
    print("name=$name");
  }

  print(name == "ada" ? "ada1" : "fial");

  println(name);
}

class Wrold {
  var name = "1";

  Wrold(this.name);
}
//as的使用，as用来做类型转化
//判断对象是否为XX类  b is Apple

class Banane {
  var weight;
  var color;

  Banane(this.weight, this.color);

  void showWeight() {
    print("weight=$weight");
  }

  void showColor() {
    print("color=$color");
  }
}

void testException() => throw "exception";

class Tree {
  var desc;

  Tree.init() {
    desc = "this is a seed";
  }

  Tree(var des) : desc = des;
}

class Fruit {
  Fruit() {
    print("this is fruit");
  }

  Fruit.desc(var desc) {
    print("$desc");
  }
}

class Apple extends Fruit {
  Apple() : super() {
    print("is it");
  }

  Apple.desc(var desc) {
    print("$desc");
  }
}

class LogUtils {
  void log() {
    print("this is a log");
  }
}

class Fruit1 {
  Fruit1() {
    print("this is furit1");
  }
}

class Apple1 extends Fruit1 with LogUtils {
  Apple1() : super() {
    print("this is apple");
  }
}

class Bjc {
  var desc;

  Bjc(this.desc);

  void log() {
    print("${this.desc}");
  }
}

class Banana {
  var desc;

  Banana(this.desc);

  void log() {
    print("${this.desc}");
  }
}

class FruitFactory<T> {
  T produceFutit(T t) {
    return t;
  }
}