[学习官方例子]TCustomComparer

代码如下：

program TCustomComparerTest;

{$APPTYPE CONSOLE}

uses
  SysUtils, Generics.Defaults, Generics.Collections;

type
  TCustomerStringComparer = class(TCustomComparer<String>)
  public
    function Compare(const Left, Right: String): Integer; override;
    function Equals(const Left, Right: String): Boolean; override;
    function GethashCode(const Value: String): Integer; override;
  end;
  { TCustomerStringComparer }

function TCustomerStringComparer.Compare(const Left, Right: String): Integer;
begin
  Result := CompareText(Left, Right);
end;

function TCustomerStringComparer.Equals(const Left, Right: String): Boolean;
begin
  Result := CompareText(Left, Right)=0;
end;

function TCustomerStringComparer.GethashCode(const Value: String): Integer;
begin
  Result := Length(Value);
end;

procedure btSortClick();
var
  List: TList<string>;
  i: Integer;
begin
  List := TList<string>.Create(TCustomerStringComparer.Create());

  for i := 0 to 5 do
    List.Add('第'+IntToStr(8-i)+'个数');

  List.Sort;
  for i := 0 to 5 do
    writeln(List[i]);
  List.Free;
end;

procedure btCountClick();
var
  Dictionary: TDictionary<String, Cardinal>;
  i: Integer;
  AString: string;
begin
  Dictionary := TDictionary<String, Cardinal>.Create(TCustomerStringComparer.Create());

  for i := 0 to 5 do
  begin
    AString := '第'+IntToStr(i)+'个数';
    if Dictionary.ContainsKey(AString) then
      Dictionary[AString] := Dictionary[AString] + 1
    else
      Dictionary.Add(AString,  1);
  end;

  for AString in Dictionary.Keys do
    writeln(AString+':'+UIntToStr(Dictionary[AString]));

  Dictionary.Free;



end;

begin
  writeln('btSortClick:');
  btSortClick;
  writeln(#10,'btSortClick:');
  btCountClick;

  readln;
end.

效果图：