Help: Problem with data types and classes

Question

Hi there,
I'm currently struggling with getting a class to read in data from a file and from that select the correct constructor to use... Basically I read a line in from a file as follows:
<String Make>:<String model>:<String registrationNumber>:<String engineSize>
e.g.
Ford:Focus:HG42EG:1800
There is an Interface called Car, of which 'Ford' is an implementation along with 'Vauxhall', 'Chrysler', etc...
From this I wish to construct a new instance of a Ford called Focus with input parameters (RegNumber registration,int engineSize) i.e.
Car Focus = new Ford(HG4 2EG,1800);So far I can convert the engineSize String into an integer and can construct the RegNumber (a class of mine) but can only get it to construct a Ford by using a switch, i.e:
switch (modelKey){
case 'f': new Ford(); break;
case 'v': new Vauxhall(); break;
case 't': new Toyota(); break;
etc...
Now I do get this to work correctly but I'm concerned that it is not OOP therefore is the way I can get code to convert the String 'Ford' into Car 'Ford'.???
Many thanks in advance for any advice you can throw my way,
Leebo

Answer 1

What is this anyway???
If Car is an interface you can't create instances of it....No, if Car is an interface, his code should be (depending on what the RegNum constructor looks like:
Car Focus = new Ford(new RegNum("HG42EG"),1800);It's the same as:
List someList = new ArrayList();However, he won't be able to use a word read from the file as a variable name "Focus". He'll need a Map:
Map myCarMap = new HashMap();
myCarMap.put("Focus", new Ford(new RegNum("HG42EG"), 1800));(Could be defined as "Map<String, Car>" if he wants to use generics.)