// 泛型

abstract class ObjectCache<T> {
  getByKey(String key);
  void setBykey(String key, Object value);
}

class FlieCache<T> implements ObjectCache<T> {
  @override
  getByKey(String key) {
    // TODO: implement getByKey
    throw UnimplementedError();
  }

  @override
  void setBykey(String key, Object value) {
    // TODO: implement setBykey
    print('文件缓存');
  }
}

练习 代码

练习.png

void main(List<String> args) {
  print("你好 dart");
  print("你好 dart1");
  var str = '字符串';
  str = '你好str';
  print(str);
  final pai = '3.14159236';
  print(pai);
  final atime = DateTime.now();
  print(atime);
  const btime = "常量"; //DateTime.now();
  print(btime);
  var str1 = """
  dart 
  dart 
  dart 
  三个单双引号也可以
  """;
  print(str1);
  var nihao1 = "你好";
  var nihao2 = "dart";
  print(nihao1 + nihao2);
  print("&nihao1 &nihao2");
  int aint = 5;
  print(aint);
  double bdouble = 2.4566;
  print(bdouble);
  bdouble = 8.1111;
  print(bdouble);
  print(aint + bdouble);
  print(aint * bdouble);
  if (bdouble > aint) {
    print("大大大");
  } else {
    print("小小小");
  }
  if (bdouble == aint) {
    print("等于等于");
  } else {
    print("不等于");
  }
  // 集合
  var list1 = ["张三", 25, true];
  print(list1);
  print(list1.length);
  print(list1[0]);
  print(list1[1]);
  var list2 = <String>["字符串", "25", "指定类型"];
  print(list2);
  var list3 = <int>[25, 28, 30];
  print(list3);
  var list4 = [];
  print(list4);
  print(list4.length);
  list4.add("组合");
  list4.addAll(list3);
  print(list4);
  var list5 = List.filled(2, list3);
  print(list5);
  var list6 = List.filled(2, list5);
  print(list6);
  list2.length = 1;
  print(list2);
  // list6[0].length = 1;
  // print(list6);
  // print([person objectKeys("name")]);
  var list7 = List.filled(1, list1);
  print(list7);
  var model = Map();
  model = {
    "name": "老六",
    "age": 30,
    "work": ["工程师", "老师"]
  };
  print(model);
  var p = Map();
  p["name"] = "哈哈哈";
  print(p);
}

网络 http

创建 pubspec.yaml 文件
文件内容

name: xxx
description: hahahahahahaa
descripter: pubtest
environment:
  sdk: '>=2.10.0 <3.0.0'
dependencies: 
  http: ^0.13.5
  

练习http.png

参考