Delphi 2009 泛型容器单元(Generics.Collections)[4]: TDictionary

TDictionary 类似哈希表.

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本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Memo1: TMemo;

    Edit1: TEdit;

    Edit2: TEdit;

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    Button4: TButton;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

    procedure Button4Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses Generics.Collections; {Delphi 2009 新增的泛型容器单元}



var

  Dictionary: TDictionary<Cardinal,string>;  

  {定义一个泛型 TDictionary 类, 指定有 Cardinal、string 构成}



{建立}

procedure TForm1.FormCreate(Sender: TObject);

begin

  Dictionary := TDictionary<Cardinal,string>.Create;



  Memo1.Clear;

  Button1.Caption := Button1.Caption + ' 添加';

  Button2.Caption := Button2.Caption + ' 删除';

  Button3.Caption := Button3.Caption + ' 尝试取值';

  Button4.Caption := Button4.Caption + ' 清空';



  Edit1.Clear;

  Edit2.Clear;

  Edit1.NumbersOnly := True;

end;



{释放}

procedure TForm1.FormDestroy(Sender: TObject);

begin

  Dictionary.Free;

end;



{添加}

procedure TForm1.Button1Click(Sender: TObject);

var

  key: Cardinal;

  value: string;

  str: string;

  k,v: Boolean;

begin

  key := StrToIntDef(Edit1.Text, 0);

  value := Edit2.Text;

  if value = '' then value := 'Null';



  k := Dictionary.ContainsKey(key);     {Key 是否存在}

  v := Dictionary.ContainsValue(value); {Value 是否存在}

  

  if not k then

  begin

    Dictionary.Add(key, value);

    Memo1.Lines.Add(Format('%d=%s', [key, value])); {同步显示}

  end;



  if k and not v then

  begin

    str := Format('key 已存在: %d=%s; 是否修改其值?', [key, Dictionary[key]]);

    if MessageBox(0, PChar(str), '提示', MB_OKCANCEL or MB_ICONQUESTION) = mrOk then

    begin

      //Dictionary[key] := value; {Dictionary[key] = Dictionary.Item[key]}

      Dictionary.AddOrSetValue(key, value);       {也可使用上一句}

      Memo1.Lines.Values[IntToStr(key)] := value; {同步显示}

    end;

  end;



  if k and v then

  begin

    str := Format('%d=%s 已存在, 不能重复添加', [key, value]);

    MessageBox(0, PChar(str), '错误', MB_OK + MB_ICONHAND);

  end;



  Text := IntToStr(Dictionary.Count);

end;



{删除: Remove}

procedure TForm1.Button2Click(Sender: TObject);

var

  key: Integer;

  i: Integer;

begin

  key := StrToIntDef(Edit1.Text, 0);



  if not Dictionary.ContainsKey(key) then  

  begin

    ShowMessageFmt('key: %d 不存在', [key]);

    Exit;

  end;

    

  Dictionary.Remove(key);

  Text := IntToStr(Dictionary.Count);

  

  {同步显示}

  i := Memo1.Lines.IndexOfName(IntToStr(key));

  if i > -1 then Memo1.Lines.Delete(i);

end;



{尝试取值: TryGetValue}

procedure TForm1.Button3Click(Sender: TObject);

var

  key: Integer;

  value: string;

begin

  key := StrToIntDef(Edit1.Text, 0);

  if Dictionary.TryGetValue(key, value) then

    ShowMessageFmt('key: %d 已存在, 其值是: %s', [key, value])

  else

    ShowMessageFmt('key: %d 不存在', [key])

end;



{清空: Clear}

procedure TForm1.Button4Click(Sender: TObject);

begin

  Dictionary.Clear;

  Text := IntToStr(Dictionary.Count);

  Memo1.Clear; {同步显示}

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 165

  ClientWidth = 275

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  PixelsPerInch = 96

  TextHeight = 13

  object Memo1: TMemo

    Left = 0

    Top = 0

    Width = 133

    Height = 165

    Align = alLeft

    Font.Charset = DEFAULT_CHARSET

    Font.Color = clWindowText

    Font.Height = -13

    Font.Name = 'Courier New'

    Font.Style = []

    Lines.Strings = (

      'Memo1')

    ParentFont = False

    ScrollBars = ssBoth

    TabOrder = 0

    ExplicitHeight = 176

  end

  object Button1: TButton

    Left = 139

    Top = 40

    Width = 128

    Height = 25

    Caption = 'Button1'

    TabOrder = 1

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 139

    Top = 71

    Width = 128

    Height = 25

    Caption = 'Button2'

    TabOrder = 2

    OnClick = Button2Click

  end

  object Button3: TButton

    Left = 139

    Top = 102

    Width = 128

    Height = 25

    Caption = 'Button3'

    TabOrder = 3

    OnClick = Button3Click

  end

  object Edit1: TEdit

    Left = 139

    Top = 8

    Width = 40

    Height = 21

    TabOrder = 4

    Text = 'Edit1'

  end

  object Edit2: TEdit

    Left = 185

    Top = 8

    Width = 81

    Height = 21

    TabOrder = 5

    Text = 'Edit2'

  end

  object Button4: TButton

    Left = 139

    Top = 133

    Width = 128

    Height = 25

    Caption = 'Button4'

    TabOrder = 6

    OnClick = Button4Click

  end

end