Self-Referring classes

[DaDeliMan]

I have a Java quesion that is probrably pretty basic.
I am looking to create a class which has a child class. I want that child class to have a reference to it's parent class and vice-versa.
When initializing it, how to I create that connected reference in Java without pointers?

Would the constructor look like

Class1 class1 = new Class1();
class1.setClass2(new Class2(this));

In other words, how do I have a class pass a reference of itself to another class?


Thanks,
Bob

 

[scrat]

Hi Bob,

Could I just clarify something. Do you want a parent to be able to have many children, or are you looking for a one-to-one relationship?

scrat

 

[DaDeliMan]

Oh, I'm sorry. Yes, I would like the parent to have a reference to many children, and each of of the childen to have a reference to the parent.

 

[scrat]

Hi Bob,

I would do something like this...

public class Parent {

Collection children = new ArrayList();

public void addChild(Child child) {
children.add(child);
}

public void doSomethingWithChildren() {
Iterator iterator = children.iterator();
while (iterator.hasNext()) {
Child child = (Child) iterator.next();
// Do something with the child...
}
}
}

public class Child {

private Parent parent;

public Child(Parent parentArg) {
parent = parentArg;
parent.addChild(this);
}
}

When a Child is created, it has a reference to a Parent, which it keeps in the parent member variable. It also calls the addChild method in the parent, passing itself to the parent so that the parent can add a reference of the child to its list of children. I have also included a snipet as an example of the parent doing something with the children. Hope this makes sense. If anything is unclear, let me know.

Regards,
scrat

 

[scrat]

P.S.

Forgot the import statements in Parent...

import java.util.Collection;
import java.util.ArrayList;
import java.util.Iterator;

public class Parent {

Collection children = new ArrayList();

public void addChild(Child child) {
children.add(child);
}

public void doSomethingWithChildren() {
Iterator iterator = children.iterator();
while (iterator.hasNext()) {
Child child = (Child) iterator.next();
// Do something with the child...
}
}
}

 

[DaDeliMan]

Cool, thanks.

Would the following code snipped be cool...

Parent p = new Parent();
p.addChild(this);


Thanks a ton,
Bob