详测 Generics Collections TDictionary(4): OnKeyNotify、OnValueNotify

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Generics.Collections;

type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
procedure KeyNotify(Sender: TObject; const Item: string;
Action: TCollectionNotification);
procedure ValueNotify(Sender: TObject; const Item: Integer;
Action: TCollectionNotification);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.KeyNotify(Sender: TObject; const Item: string;
Action: TCollectionNotification);
begin
case Action of
cnAdded     : ShowMessageFmt('Key_Add: %s', [Item]);
cnRemoved   : ShowMessageFmt('Key_Remove: %s', [Item]);
cnExtracted : ShowMessageFmt('Key_Extract: %s', [Item]);
end;
end;

procedure TForm1.ValueNotify(Sender: TObject; const Item: Integer;
Action: TCollectionNotification);
begin
case Action of
cnAdded     : ShowMessageFmt('Value_Add: %d', [Item]);
cnRemoved   : ShowMessageFmt('Value_Remove: %d', [Item]);
cnExtracted : ShowMessageFmt('Value_Extract: %d', [Item]);
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
Dictionary: TDictionary<string,Integer>;
begin
Dictionary := TDictionary<string,Integer>.Create();
Dictionary.OnKeyNotify := KeyNotify;
Dictionary.OnValueNotify := ValueNotify;

Dictionary.Add('n1', 111); {Key_Add: n1;  Value_Add: 111}
Dictionary.Add('n2', 222); {Key_Add: n2;  Value_Add: 222}

Dictionary.AddOrSetValue('n1', 123); {Value_Remove: 111;  Value_Add: 123}

Dictionary.Remove('n1');      {Key_Remove: n1;  Value_Remove: 111}

Dictionary.ExtractPair('n2'); {Key_Extract: n2;  Value_Extract: 222}

Dictionary.OnKeyNotify := nil;
Dictionary.OnValueNotify := nil;

Dictionary.Free;
end;

end.