That's perfect, I appreciate very much your help my friends.
I'm sorry Gianny, the fact is that I didn't understand your first mail about this subject because I didn't know the Timestamp class yet. Always used Calendar and Date (even if this last one is almost completely deprecated.
The java.sql.Timestamp class has a static method called valueOf to convert Strings in the format
yyyy-mm-dd hh:mm:ss.fffffffff(where ffffffffff represents nanoseconds) to a java.sql.Timestamp instance. As pointed out previously, this is easier than writing your own converter. See Javadocs for java.sql.Timestamp for more info.
In your Entity Bean class you would declare the field like the following:
public abstract java.sql.Timestamp getstartDate();
public abstract void setStartDate(java.sql.Timestamp newStartDate);
And then you can use Timestamp.valueOf(String yourStartDateAsString) to convert as appropriate.