Dear all,

What's the preferred way to get an iterator that iterates over all elements
of an unsorted list, in sorted order? My approach was to create a copy of
the list, sort it and then return the sorted list's iterator.

This seems crude ... is it?

Cheers,
David

public Iterator getSortedIterator() {
        List l = new ArrayList();
        l.addAll(myCollection.values());
        Collections.sort(l, new FooModelComparator());
        return l.iterator();
    }
 
private static class FooModelComparator implements Comparator {
        public int compare(Object o1, Object o2) {
            Foo s1 = (Foo) o1;
            Foo s2 = (Foo) o2;
            return s1.getId().compareTo(s2.getId());
        }
    }

 

 

If getSortedIterator is a method of a List class, then I think that's not a good idea. If it's in some other class that's using a List, go for it.

 

 

No, I think it's about the best you could do algorithmically. Your code could be improved though:

public Iterator getSortedIterator() {
    List l = new ArrayList(myCollection.values());
    Collections.sort(l, new Comparator() {
            public int compare(Object o1, Object o2) {
                Foo s1 = (Foo) o1;
                Foo s2 = (Foo) o2;
                return s1.getId().compareTo(s2.getId());
            }});
 
    return l.iterator();
}

 

 

can do it all in one place, write a iterator class

import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
 
/** SortedIterator
 * @author CNLohfin3109
 * Created on Apr 11, 2005
 */
public class SortedIterator implements Iterator {
       private Object o[];
       int i;
       public SortedIterator(Collection c){
           	o = c.toArray();
          	Arrays.sort(o);
          	i=0;
       }
 
       public Object next(){
           return o[i++];
       }
 
       public boolean hasNext(){
          return ( i < o.length );
       }
 
       public void remove(){
           throw new UnsupportedOperationException();
       }
}

then just have your method return new SortedIterator(myCollection);