Re: A list of ever member in a class.

From:
Daniel Gee <zefria@gmail.com>
Newsgroups:
comp.lang.java.help
Date:
23 Apr 2007 16:30:58 -0700
Message-ID:
<1177371058.868913.54070@n76g2000hsh.googlegroups.com>

<nitpicking>
</nitpicking>


Ah, right. I get those names often mixed up because the teacher who
gave me the first formal introduction to the subject was actually a C+
+ programmer who wasn't used to teaching in Java.

Right then, "generics" it is.

public class MemberHolder<T>
{
public T[] mymembers;

public MemberHolder(int numberToHold)
{
mymembers = new T[numberToHold];
}

}


Unfortunately this won't work. Mixing generics and arrays is never a
good idea, and in this case the compiler won't even let you: you can't
create an array of generic types. There's a section in the JLS
explaining why this is, but I'm afraid I can't remember where exactly.


but...... sections from the source for java.util.ArrayList itself
read:

public class ArrayList<E> extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable,
java.io.Serializable
{
    private transient E[] elementData;
....
    public ArrayList(int initialCapacity) {
    super();
        if (initialCapacity < 0)
            throw new IllegalArgumentException("Illegal Capacity: "+
                                               initialCapacity);
    this.elementData = (E[])new Object[initialCapacity];
    }
....
}

Does the casting make all the difference?

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