Re: Determine index from array reference?

From:

Knute Johnson <nospam@rabbitbrush.frazmtn.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 24 Jan 2007 21:11:02 -0800

Message-ID:

<EZWth.89575$Yu6.19610@newsfe16.lga>

Lew wrote:

Why ignore the advice to use ArrayList?

What's the aversion to Vector?

public class test1 {
    public static void main(String[] args) {
        Vector<JTextField> v = new Vector<JTextField>();
        JTextField test = null;

        for (int i=0; i<10; i++) {
            JTextField tf = new JTextField(" ",10);
            v.add(tf);
            if (i == 3)
                test = tf;
        }

        System.out.println(v.indexOf(test));
        System.out.println(v.indexOf(null));
    }
}

Bear in mind that these are first occurrences of these values in the List.

Well there shouldn't be other occurrences or it won't work at all.

If you plan to use the result of your "indexOf()" to locate another
object, rather than just println() it, you might consider using a
Map <JTextField, OtherType>. That would have the benefit of constant
time lookup (if you use HashMap) instead of O(n). You also avoid bugs
caused by "parallel" Lists going non-Euclidean.

- Lew

I don't think that saves me anything over the original scheme and just
makes it more complicated.

--

Knute Johnson
email s/nospam/knute/