Re: generic sorting?

Hi group,

I want to thank all of you for your help, I tried out what you told me
and think it's really great.

First of all, I have replaced all "int"s with Integer, because Java's
"int"s don't really support genericity. So that's fine now.

Second, I have implemented WeightedObjects like this:
public class WeightedObject<T, C extends Comparable<C>>
          implements Comparable<WeightedObject<T, C>>
{
public final T t;
public final C c;

public WeightedObject(T tt, C cc)
{
    c = cc;
    t = tt;
}

public int compareTo(WeightedObject<T, C> o)
{
    return c.compareTo(o.c);
}

} // class

My application code becomes really simple, then:
List<WeightedObject<Plot, Integer>> plots_with_distance
   = new Vector<WeightedObject<Plot, Integer>>();
for (Plot plot : plots)
{
    plots_with_distance.add(new WeightedObject<Plot, Integer>
                                             (plot,
(int)p.distance_to(plot.point))
                                           );
}
Collections.sort(plots_with_distance);

(I only use the (int) cast to round from a double, so that's no typing
problem. I just don't want to sort by the decimal fraction...)

Third, for learning, I have also changed my original approach to use
Integer and that gives a nice example:

package bob.util;

import java.util.Arrays;
import java.util.Comparator;

public class IndirectComparator<T extends Comparable<T>> implements
Comparator<Integer>
{
protected T[] weight;

public IndirectComparator(T[] w)
{
    weight = w;
}

public int compare(Integer i, Integer j)
{
    return (weight[i].compareTo(weight[j]));
}

public static <T extends Comparable<T>> void sort(Integer[] index, T[]
weight)
{
    Arrays.sort(index, new IndirectComparator<T>(weight));
}

}

It's not as clear as what you suggested, but I like it, too. ;-)

Cheers,
Bob