Tukukkk

I currently have two classes, Universe and World. The Universe class has a ArrayList field, that lists all of that Universe's Worlds. I want to be able to copy a Universe and then add a world to it, so that I have two Universe objects, one with one World less than the other.

This is the Universe class:

public class Universe {

    private ArrayList<World> worlds;

    private int worldCount;

    private boolean reflex;

    private boolean trans;

    private boolean symm;

    private boolean hereditary;



    public Universe(ArrayList<World> worlds, int worldCount, boolean reflex, boolean trans, boolean symm, boolean hereditary) {

        this.worlds = worlds;

        this.worldCount = worldCount;

        this.trans = trans;

        this.reflex = reflex;

        this.symm = symm;

        this.hereditary = hereditary;

        if (this.symm && this.trans) { // symmetry and transitivty makes reflexivity

            this.reflex = true;

        }

    }

    public Universe(Universe u) { // creates a shallow copy of the other universe

        this(u.getWorlds(), u.getWorldCount(), u.getReflex(), u.getTrans(), u.getSymm(), u.getHereditary());

    }

    @Override

    public Object clone() {

        Universe u = null;

        try {

            u = (Universe) super.clone(); 

        }catch(CloneNotSupportedException e) { 

            u = new Universe(this.getWorlds(), this.getWorldCount(), this.getReflex(), this.getTrans(), this.getSymm(), this.getHereditary());

        } 

        return u;

    }

}

And the World class:

public class World {

    private Universe parentUniverse;

    private String worldName;

    private ArrayList<Relation> relations; 

    private ArrayList<ExprStr> expressions;





    public World(Universe u) {

        this.parentUniverse = u;                 

        int count = u.getWorldCount();

        String countStr = Integer.toString(count);

        this.worldName = "";

        this.worldName += 'w' + countStr;

        this.relations = new ArrayList<Relation>();

        if (this.parentUniverse.getReflex()) {

            this.addRelation(this, true, true); 

        }

        this.expressions = new ArrayList<ExprStr>();

    }

}

The World class names itself within its own universe, and the toString method returns that name. The toString method of Universe returns the list of all Worlds.

I have the code:

Universe y = new Universe();

World d = new World(y);

y.addWorld(d);



Universe x = (Universe) y.clone(); // have to type cast to use clone()

World d1 = new World(x);

x.addWorld(d1);



System.out.println(y);

System.out.println(x);

But the output is:

[w0, w1]

[w0, w1]

Even though, if deep copied properly, I expected that one Universe would have more worlds than the other.

Do I need to deep copy the World class too? What am I doing wrong?

Thanks heaps! :)