访问TDictionary项目

Question

我正在使用embarcadero示例( http://docwiki.embarcadero.com/CodeExamples/XE5/en/Generics_Collections_TDictionary_%28Delphi%29 )测试TDictionary。

创建和添加键和值没有问题。但是，当我尝试使用键值‘London’访问该表时：

(1) Dictionary.Items‘’London‘.Country ->给出了正确的值“Dictionary.Items’‘London’.Country‘

(2)在Edit1.Text中输入'London‘，然后Dictionary.ItemsEdit1.Text.Country ->给出错误"the item not found“？

有没有人能解释一下？

提前谢谢。

/

var Dictionary: TDictionary<String, TCity>;
    City, Value: TCity;
    Key: String;


begin
  Dictionary := TDictionary<String, TCity>.Create;
  City := TCity.Create;
  { Add some key-value pairs to the dictionary. }
  City.Country := 'Romania';
  City.Latitude := 47.16;
  City.Longitude := 27.58;
  Dictionary.Add('Iasi', City);

  City := TCity.Create;
  City.Country := 'United Kingdom';
  City.Latitude := 51.5;
  City.Longitude := -0.17;
  Dictionary.Add('London', City);

  City := TCity.Create;
  City.Country := 'Argentina';
  { Notice the wrong coordinates }
  City.Latitude := 0;
  City.Longitude := 0;
  Dictionary.Add('Buenos Aires', City);

  showmessage(Dictionary.Items['London'].Country); // This One is OK

  // now using Edit1.Text where I put 'London'
  Showmessage(Dictionary.Items[Edit1.Text].Country); // This return to error message (Item not found)


  Dictionary.Clear;
  Dictionary.Free;
  City.Free;

end;

Answer 1

解释是，与您声称的相反，Edit1.Text不等于'London'。可能字母大小写不匹配。或者有前导空格或尾随空格。

添加断言以验证我是否正确：

Assert(Edit1.Text='London');