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Collections - Linked list

Justin Fox
Ranch Hand

Joined: Jan 24, 2006
Posts: 802
ok, here is my Number class....

can this be referenced as a node?...or element of a list?
because I went to the API and looked under list in the java.util,
and it said it had a add()method. but I read on further down
and it says its a boolean method.

well any ways. here is my main class.

now the List compiles fine, but when i try to do mylist.add(one);
, it doesn't want to compile, says it can't find the method add().

so do i need to make my own class and define an add method?

and also, in my book, it shows this as an example of a node.

So could i create a whole bunch of Node classes?...and add them to a List?

like for example..

class Node1
int info;
Node1 next;

but what i dont under stand is... what would Node1 point to?
which ever element is added next?

until I add one that is defined?
like so:

but when i declare it in a main class..
there is not public modifier...

so would i just do

Node3 node3 = new Node3();?


Node3 node3;
- and if i did do it like this, would the info be passed on?

Thanks for the help


You down with OOP? Yeah you know me!
Henry Wong

Joined: Sep 28, 2004
Posts: 19926

When you instantiate a List object, you are not instantiating a collection. Instead, you are instantiating your own class. The reason that the add() method doesn't exist, is because you never created one.


Books: Java Threads, 3rd Edition, Jini in a Nutshell, and Java Gems (contributor)
M. Bunyard

Joined: Mar 28, 2006
Posts: 3

From the imported java.util.* package, it appears that you are trying to instantiate a java.util.List object. A java.util.List object cannot be instantiated due to the fact that it is an interface, but you can do the following if the Collections List is what your after:

The "java.util" is pre-pended when defining the mylist variable to remove the ambiguity in which List class (or interface) to use (either predefined java.util.List interface or your List class).
Don't get me started about those stupid light bulbs.
subject: Collections - Linked list
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