Accessing the same object from multiple classes.

Question

For the life of me I can't workout how I can access things from classes that haven't created them.
I don't want to have to use "new" multiple times in seperate classes as that would erase manipulated values.
I want to be able to access and manipulate an array of objects from multiple classes without resetting the array object values. How do I create a new object then be able to use it from all classes rather than re-creating it?
Also I need my GUI to recognize the changes my buttons are making to data and reload itself so they show up.
All help is good help!
regards,
Luke Grainger

Answer 1

As long as you have a headquarters it shouldn't be to painfull. You simply keep a refrence to your ShipDataBase and Arsenal and all your irrellevant stuff in Headquarters. So the start of your Headquarters class would look something like:
public class Headquarters{
  public Arsenal arsenal;
  public ShipDatabase db;
//constructor
  public Headquarters(){
    arsenal = new Arsenal(this, ....);
    db = new ShipDatabase(...);
//The Arsenal class:
public class Arsenal{
  public Headquarter hq;
  public Arsenal(Headquarter hq, ....){
    this.hq = hq;
    .Then in your ShipDatabase you should, as good programing goes, keep the arraylist as a private class variable, and then make simple public methods to access it. Methods like getShipList(), addToShipList(Ship ship)....
So when you want to add a ship from arsenal you write:
hq.db.addToShipList(ship);
.Or you could of course use a more direct refrence:
ShipDatabase db = hq.db;
or even
ShipList = hq.db.getShipList();
but this requires that the shiplist in the DB is kept public....
Hope it was comprehensive enough, and that I answered what you where wondering.
Sjur
PS: Initialise the array is what you do right here:
//constructor
shipList = new Ship[6];
shipList[0] = new Ship("Sentry", 15, 10, "Scout");
" " " "etc
shipList[5] = new Ship("Sentry", 15, 10, "Scout");PPS: To make code snippets etc. more readable please read this article:
http://forum.java.sun.com/faq.jsp#messageformat