flutter 年终复习

1. flutter中的数据类型int、double、num、string、List、Map、bool、set,类型判断用is

    var text = "112";
    if (text is String) {
      print("是字符串");
    } else {
      print("不是字符串");
    }

2. Set类型和数组一样只不过去重

 //使用set滤重
   List myList = ["苹果","香蕉","椰子","橙子","香蕉","苹果"];
    var s = new Set();
    s.addAll(myList);
    print(myList);  //[苹果, 香蕉, 椰子, 橙子, 香蕉, 苹果]
    print(s); //{苹果, 香蕉, 椰子, 橙子}
    print(s.toList()); //[苹果, 香蕉, 椰子, 橙子]

3. Map类型

//map类型
  Map person = {"name":"张三","age":20,"sex":"男"};
  print(person.keys);   //(name, age, sex)
  print(person.keys.toList());  //[name, age, sex]
  print(person.isEmpty);  //false
  print(person.isNotEmpty);  //true
  person.addAll({
    "work":"外卖"
  });
  print(person);

4.循环

 List myList = ["苹果","香蕉","椰子","橙子","香蕉","苹果"];
  
  //1.
  for(var item in myList){
//     print(item);
  }
  //2
  myList.forEach((value){
//     print(value);
  });
  
  //3
  List nList = [1,2,3];
  var newList = nList.map((value){
    return value * 2;
  });
//   print(newList);   //(2, 4, 6)
//   print(newList.toList());  //[2, 4, 6]
  
  //4. any 代表数组中有一个大于5就为true, where代表所有的都>5
   List nList1 = [1,2,3,4,5,6,7];
  var result1 = nList1.any((value){
    return value > 5;
  });  //true
   print(result1);
  var result2 = nList1.every((value){
    return value > 5;
  });  //false
   print(result2);
  
  //5where
  var result3 = nList1.where((value){
    return value > 5;
  });  //false
   print(result3); //(6, 7)
  print(result3.toList());  //[6, 7] 

4. ..级联操作符,更简便的给对象属性赋值

 Person p = Person();
  //赋值的正常写法
  // p.name = "张三";
  // p.age = 15;
  // p.printInfo();

  //级联操作符写法
  p
    ..name = "张三"
    ..age = 15;
  p.printInfo();

5. abstract抽象类、继承extents、接口implements、mixin

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6. 泛型

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7. 空安全

• 2.13版本之后加入的 主要有?、!、late、@request等关键字

8. flutter 常量 const final identical 无状态组件性能优化

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9. image组件加载不同分辨率的图片

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10. 路由跳转

• 普通路由跳转
• 命名路由跳转
• 第三方 fluro 、getx

最全的路由跳转操作