The code below converts a java.sql.Timestamp value returned by java.sql.Timestamp.getTime() into a .NET DateTime value.

As the Java.sql.Timestamp value is the number of milliseconds since 1st Jan 1970 00:00:00 GMT, to convert the value into a .Net DateTime value, we simply create a DateTime record of 1st Jan 1970 00:00:00 GMT, and add the number of milliseconds into it.

function JavaBaseToNETDateTime(ALong: Int64): DateTime;
var
  LBaseDateTime: DateTime;
  TS: TimeSpan;
begin
  LBaseDateTime := DateTime.Create(1970, 1, 1);
  TS := TimeSpan.FromMilliseconds(ALong);
  Result := LBaseDateTime.AddMilliseconds(ALong).ToLocalTime;
end;

The above is one of the functions I had to write when I had to convert a Java application to a Delphi.NET application.