Re: passing a Factory to a method to create a generic instance
On Sat, 10 May 2008 01:19:13 +0100, Tom Anderson wrote:
Before i go on, i should say that in the classical application of the
Factory pattern, yes, you would make something more specific than an
Object, because the different factories would be making different
versions of something, or the same thing in different ways. Like you
might define a WidgetFactory, then have concrete factories that make
Nut, Bolt, Screw, etc objects, all of which are subtypes of Widget.
Does there have to be a Nut factory, or can I just use the Widget factory?
I'm not seeing the advantage of WidgetFactory, because I don't seem able
to use it. For me, DataFactory rather than WidgetFactory:
Guest extends Data //Data is just the name of package
Room extends Data //non-inspiring name
public class DataFactory implements Factory<Data> {
public Data make(List<String> data) {return new Data(data);}
}
public interface Factory <T>{
public T make(List<String> data);
}
This is the error:
a00720398/bedz/Bedz.java:24: incompatible types
found : java.util.List<a00720398.data.Data>
required: java.util.List<a00720398.data.Room>
rooms = FileUtil.load(roomsFile, new DataFactory());
^
1 error
thufir@arrakis:~/bcit-comp2611-project1$
thufir@arrakis:~/bcit-comp2611-project1$ cat src/a00720398/bedz/Bedz.java
package a00720398.bedz;
public class Bedz {
//deleted some stuff
public static void main (String[] args){
/* how do I pass a DataFactory()?
rooms = FileUtil.load(roomsFile, new DataFile()); //error
*/
rooms = FileUtil.load(roomsFile, new RoomFactory());
guests = FileUtil.load(guestsFile, new GuestFactory());
FileUtil.output(rooms,new File("out.txt"));
}
}
thufir@arrakis:~/bcit-comp2611-project1$
thanks,
Thufir