Dart編程語言入門學(xué)習(xí)

ChanceWong 發(fā)布于2019-05-22 18:35 / 1513人閱讀

摘要：數(shù)據(jù)類型不可變不可變

1.數(shù)據(jù)類型 Boolean

void main(){
  bool isTrue = true;
  bool isFalse = false;

  print("Hello".isEmpty);
}

Number

void main(){
  num a = 10;
  a = 12.5;

  int b = 20;
//  b = 20.5;

  double c = 10.5;
//  c = 30;

  print(b + c);
  print(b - c);
  print(b * c);
  print(b / c);
  print(b ~/ c);
  print(b % c);

  print(0.0 / 0.0);

  print(b.isEven);
  print(b.isOdd);
  int d = 11;
  print(d.isEven);
  print(d.isOdd);

  int e = -100;
  print(e.abs());

  double f = 10.5;
  print(f.round());
  print(f.floor());
  print(f.ceil());

  print(f.toInt());
  print(d.toDouble());

}

String

void main(){
  String str1 = "Hello";//""
  String str2 = """Hello
                  Dart""";//"""
  print(str2);

//  String str3 = "Hello 
 Dart";
  String str3 = r"Hello 
 Dart";
  print(str3);

  String str4 = "This is my favorite language";
  print(str4 + "New");
  print(str4 * 5);
  print(str3 == str4);
  print(str4[1]);

  int a = 1;
  int b = 2;
  print("a + b = ${a + b}");
  print("a = $a");

  print(str4.length);
  print(str4.isEmpty);

  print(str4.contains("This"));
  print(str4.substring(0,3));
  print(str4.startsWith("a"));
  print(str4.endsWith("ge"));

  var list = str4.split(" ");
  print(list);

  print(str4.replaceAll("This", "That"));
}

Const

void main(){
  var a;
  print(a);

  a = 10;
  print(a);

  a = "Hello Dart";
  print(a);

  var b = 20;
  print(b);

  final c = 30;
//  c = 50;

  const d = 20;
//  d = 50;

}

List

void main(){
  var list1 = [1,2,3,"Dart",true];
  print(list1);
  print(list1[2]);
  list1[1] = "Hello";
  print(list1);

  var list2 = const [1,2,3];  //不可變
//  list2[0] = 5;

  var list3 = new List();

  var list = ["hello","dart"];
  print(list.length);
  list.add("New");
  print(list);

  list.insert(1, "Java");
  print(list);

  list.remove("Java");
  print(list);

//  list.clear();
//  print(list);

  print(list.indexOf("dart1"));
  list.sort();
  print(list);

  print(list.sublist(1));

  list.forEach(print);
}

Map

void main(){
  var map1 = {"first":"Dart",1:true,true:"2"};
  print(map1);

  print(map1["first"]);
  print(map1[true]);
  map1[1] = false;
  print(map1);

  var map2 = const {1:"Dart",2:"Java"};//不可變
//  map2[1] = "Python";

  var map3 = new Map();

  var map = {"first":"Dart","second":"Java","third":"Python"};
  print(map.length);
//  map.isEmpty;

  print(map.keys);
  print(map.values);

  print(map.containsKey("first"));
  print(map.containsValue("C"));

  map.remove("third");
  print(map);

  map.forEach(f);

  var list = ["1","2","3"];
  print(list.asMap());
}

void f(key,value){
  print("key=$key,value=$value");
}

dynamic

void main(){
  var a;
  a = 10;
  a = "Dart";

  dynamic b = 20;
  b = "JavaScript";

  var list = new List();
  list.add(1);
  list.add("hello");
  list.add(true);
  print(list);
}

2.運(yùn)算符 operator_arithmetic

void main(){
  int a = 10;
  int b = 2;

  print(a + b);
  print(a - b);
  print(a * b);
  print(a / b);
  print(a ~/ b);
  print(a % b);

  print(a++);//11
  print(++a);//12

  print(a--);//11
  print(--a);//10
}

operator_asignment

void main(){
  int a = 10;
  int b = 5;

  b ");print(b);

  a += 2;
  print(a);

  a -= b;
  print(a);

  a *= b;
//  a /= b;
  a ~/= b;
  a %= b;

}

operator_conditional

void main(){
  int gender = 1;
  String str = gender == 0 ");"Male=$gender" :"Female=$gender";
  print(str);

  String a = "Dart";
  String b = "Java";
  String c = a ");print(c);


}

operator_logical

void main(){
  bool isTrue = true;
  print(!isTrue);

  bool isFalse = false;
  print(isTrue && isFalse);
  print(isTrue || isFalse);

  String str = "";
  print(!str.isEmpty);

}

operator_relational

void main(){
  int a = 5;
  int b = 3;

  print(a == b);
  print(a !=b );
  print(a > b);
  print(a < b);
  print(a >= b);
  print(a <= b);

  String strA = "123";
  String strB = "123";
  print(strA == strB);
}

3.控制語句 break_and_continue

void main(){
  var list = [1,2,3];
  for(var item in list){
    if(item == 2) {
//      break;
      continue;
    }
    print(item);
  }

  print("-----");
  var list2 = [4,5,6];
  for(var item1 in list){
    if(item1 == 2){
      break;
    }

    for(var item2 in list2){
      if(item2 == 5){
        break;
      }
      print(item2);
    }
  }
  
}

stmt_assert

void main(){
  String str;
  assert(str != null);
}

stmt_for

void main(){
  var list = [1,2,3,4,5];

  for(var index = 0;index < list.length;index++){
    print(list[index]);
  }

  print("---------");
  for(var item in list){
    print(item);
  }

}

stmt_if

void main(){
  int score = 100;

  if(score >= 90){
    if(score == 100){
      print("完美");
    }else {
      print("優(yōu)秀");
    }
  }else if(score > 60){
    print("良好");
  }else if(score == 60){
    print("及格");
  }else {
    print("不及格");
  }
}

stmt_switch

void main(){
  String language = "Java";

  switch(language){
    case "Dart":
      print("Dart is my favorite");
      break;
    case "Java":
      print("Java is my favorite");
      break;
    case "Python":
      print("Python is my favorite");
      break;
    default:
      print("None");
  }

  switch(language){
    Test:
    case "Dart":
      print("Dart is my favorite");
      break;
    case "Java":
      print("Java is my favorite");
      continue Test;
//      break;
    case "Python":
      print("Python is my favorite");
      break;
    default:
      print("None");
  }
}

stmt_while

void main(){
  int count = 0;

  while(count < 5){
    print(count++);
  }

  print("---$count----");

  do{
    print(count--);
  }while(count > 0 && count < 5);


}

4.方法 function_declaration

void main(List args){
  print(args);

  print(getPerson("張三", 18));

  print(printPerson("李四", 20));
}

int gender = 1;
getPerson(name,age) => gender == 1 ");"name=$name,age=$age":"Test";

printPerson(name,age){
  print("name=$name,age=$age");
}

function_optional_param可選參數(shù)

void main(){

  printPerson("李四");
  printPerson("李四",age: 20);
  printPerson("李四",age: 20,gender: "Male");
  printPerson("李四",gender: "Male");

  printPerson2("張三");
  printPerson2("張三",18);
  printPerson2("張三",18,"Female");
}

printPerson(String name,{int age,String gender}){
  print("name=$name,age=$age,gender=$gender");
}

printPerson2(String name,[int age,String gender]){
  print("name=$name,age=$age,gender=$gender");
}

function_default_param默認(rèn)參數(shù)

void main(){

  printPerson("李四");
  printPerson("李四",age: 20);
  printPerson("李四",gender: "Male");
}

printPerson(String name,{int age = 30,String gender = "Female"}){
  print("name=$name,age=$age,gender=$gender");
}

function_object方法對(duì)象

void main(){
  Function func = printHello;
  func();

  var list = [1,2,3,4];
  list.forEach(print);

  var list2 = ["h","e","l","l","o"];
  print(listTimes(list2, times));
}

void printHello(){
  print("Hello");
}

List listTimes(List list ,String times(str)){
  for(var index = 0;index < list.length;index++){
    list[index] = times(list[index]);
  }

  return list;
}


String times(str){
  return str*3;
}

function_anonymous匿名方法

void main(){

  var func = (str){
    print("Hello---$str");
  };
  func(30);

//  ((){
//    print("Test");
//  })();
  var list2 = ["h","e","l","l","o"];

  var result = listTimes(list2, (str){ return str * 3;});
  print(result);

  print(listTimes2(list2));

}

List listTimes(List list ,String times(str)){
  for(var index = 0;index < list.length;index++){
    list[index] = times(list[index]);
  }

  return list;
}

List listTimes2(List list ){
  var func = (str){ return str * 3;};

  for(var index = 0;index < list.length;index++){
    list[index] = func(list[index]);
  }

  return list;
}

function_closure閉包

void main(){
  var func = a();
  func();
  func();
  func();
  func();

}

a(){
  int count = 0;

//  printCount(){
//    print(count++);
//  }

  return (){
    print(count++);
  };
}

5.面向?qū)ο?/b> class_and_object類與對(duì)象
import "person.dart"; void main() { var person = new Person(); person.name = "Tom"; person.age = 20; print(person.name); print(person.address); person.work(); }

//person.dart class Person { String name; int age; final String address = ""; void work(){ print("Name is $name,Age is $age,He is working..."); } }
calculated_property計(jì)算屬性
void main() { var rect = new Rectangle(); rect.height = 20; rect.width = 10; print(rect.area); rect.area = 200; print(rect.width); } class Rectangle{ num width,height; num get area => width * height; set area(value){ width = value / 20; } }
constructors構(gòu)造方法
void main() { var person = new Person("Tom",20,"Male"); new Person.withName("John"); new Person.withAge(20); } class Person{ String name; int age; final String gender; Person(this.name,this.age,this.gender); Person.withName(String name){ this.name = name; } Person.withAge(this.age); void work(){ print("Work..."); } }
const_constructors常量構(gòu)造方法
void main() { const person = const Person("Tom",20,"Male"); person.work(); } class Person{ final String name; final int age; final String gender; const Person(this.name,this.age,this.gender); void work(){ print("Work..."); } }
factory_constructors工廠構(gòu)造方法
class Logger { final String name; static final Map _cache = {}; factory Logger(String name) { if (_cache.containsKey(name)) { return _cache[name]; } else { final logger = Logger._internal(name); _cache[name] = logger; return logger; } } Logger._internal(this.name); void log(String msg) { print(msg); } }
init_list初始化列表
void main() { var person = new Person("Tom", 20, "Male"); } class Person{ String name; int age; final String gender; Person(this.name,this.age,this.gender); Person.withMap(Map map): name = map["name"],gender = map["gender"]{ age = map["age"]; } void work(){ print("Work..."); } }
static_member靜態(tài)成員
void main() { var page = new Page(); Page.scrollDown(); } class Page{ static const int maxPage = 10; static int currentPage = 1; //下滑 static void scrollDown(){ currentPage = 1; print("ScrollDown..."); } //上滑 void scrollUp(){ currentPage++; print("scrollUp..."); } }
object_operator對(duì)象操作符
void main() { // Person person = new Person(); // person");""; // person = new Person(); // (person as Person).work(); // if (person is Person){ // person.work(); // } new Person() ..name = "Tom" ..age = 20 ..work(); } class Person{ String name; int age; void work(){ print("Work...$name,$age"); } }
object_call對(duì)象call
void main() { var person = new Person(); print(person("Test",30)); } class Person{ String name; int age; // void work(){ // print("Name is $name,Age is $age"); // } String call(String name,int age){ return "Name is $name,Age is $age"; } }
6.面向?qū)ο髷U(kuò)展 繼承
import "person.dart"; void main() { // var student = new Student(); // student.study(); // // student.name = "Tom"; // student.age = 16; // // print(student.isAdult); // // student.run(); Person person = new Student(); person.name = "Tom"; person.age = 18; if(person is Student){ person.study(); } print(person); } class Student extends Person{ void study(){ print("Student study..."); } @override bool get isAdult => age > 15; @override void run() { print("Student run..."); } }

class Person { String name; int age; String _birthday; bool get isAdult => age > 18; void run(){ print("Person run..."); } @override String toString() { return "Name is $name,Age is $age"; } }
繼承中的構(gòu)造方法
void main() { var student = new Student("Tom","Male"); print(student.name); } class Person{ String name; Person(this.name); Person.withName(this.name); } class Student extends Person{ int age; final String gender; Student(String name,String g) : gender = g, super.withName(name); }
抽象類
void main() { var person = new Student(); person.run(); } abstract class Person{ void run(); } class Student extends Person{ @override void run() { print("run..."); } }
接口
void main() { var student = new Student(); student.run(); } //class Person{ // String name; // // int get age => 18; // // void run(){ // print("Person run..."); // } //} abstract class Person{ void run(); } class Student implements Person{ @override void run() { print("Student run..."); } }
mixins
void main() { // var d = new D(); // d.a(); } //class A{ // void a(){ // print("A.a()..."); // } //} // //class B{ // // void a(){ // print("B.a()..."); // } // // void b(){ // print("B.b()..."); // } //} // //class Test{} // // //class C{ // // void a(){ // print("C.a()..."); // } // // void b(){ // print("C.b()..."); // } // // void c(){ // print("C.c()..."); // } //} // //class D extends A with C,B{ // //} abstract class Engine{ void work(); } class OilEngine implements Engine{ @override void work() { print("Work with oil..."); } } class ElectricEngine implements Engine{ @override void work() { print("Work with Electric..."); } } class Tyre{ String name; void run(){} } class Car = Tyre with ElectricEngine; class Bus = Tyre with OilEngine;
操作符覆寫
void main() { var person1 = new Person(20); var person2 = new Person(20); print(person1 > person2); person1.age; print(person1["age"]); print(person1 == person2); } class Person{ int age; Person(this.age); bool operator >(Person person){ return this.age > person.age; } int operator [](String str){ if("age" == str){ return age; } return 0; } @override bool operator ==(Object other) => identical(this, other) || other is Person && runtimeType == other.runtimeType && age == other.age; @override int get hashCode => age.hashCode; }
7.枚舉 enum
void main() { var currentSeason = Season.winter; print(currentSeason.index); switch(currentSeason){ case Season.spring: print("1-3月"); break; case Season.summer: print("4-6月"); break; case Season.autumn: print("7-9月"); break; case Season.winter: print("10-12月"); break; } } enum Season{ spring, summer, autumn, winter }
8.泛型 generics
void main() { var list = new List(); list.add(1); // var utils = new Utils(); // utils.put(1); var utils = new Utils(); utils.put(1); } class Utils{ void put(T element){ print(element); } // void putString(String element){ // this.elementStr = element; // } }

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