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  1. #1
    New to the CF scene
    Join Date
    Jan 2011
    Thanked 0 Times in 0 Posts

    Need help with java code! Beginner

    Hi I am a beginner with Java have been in school for a month now.
    I have a question about a school project that needs to be done.
    We are supposed to create objects that can be either a jewellry, stock or an item. These are all subclasses to Things. We also have a class called Person(they are the owners of Things), and in that class we are supposed to have an arraylist<Things>.
    My question is now. If I create an object of jewellry in the main method, how can i add it to the ArrayList<Things> in person-class.

    Please be patient with me because Im very new to this, and its not really my favourite subject

  • #2
    Codeasaurus Rex
    Join Date
    Jun 2008
    Redmond, WA
    Thanked 100 Times in 94 Posts
    Assuming your class Jewelery extends Things you should be able to just add it into ArrayList<Things>.

    So, your Java class for Jewelery would have to start something like this:

    public class Jewelery extends Things {
    With inheritance (the extends attribute), if B extends A, and there exists ArrayList<A>, then B can be added to ArrayList<A>.

    (Think of inheritance as a more specific version of a parent class. For example Rose extends Flower)

    So, you should be able to use the Java API on ArrayList to add the object, for example:

    Jewelery myJewelery = new Jewelery();
    // Invoking add( Object o ) adds the object to the end of the list
    myThingsArrayListObject.add( myJewelery );
    Where myThingsArrayListObject is the object created in Person with the array list.

    For detailed methods with the ArrayList API, consult the Java Doc: http://download.oracle.com/javase/1....ArrayList.html

    Moreover, if you have problems saying something like "Cannot reference this from a static context" then please post your complete error here with relevant lines of code and I can help you work through that. If you're new to Java and trying to modify a class' object from the main() method then you'll probably run into that problem.

    Hope this helps!
    Unless otherwise stated, any code posted is most likely untested and may contain syntax errors.
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