Sorting hash table values

import java.util.*;

@SuppressWarnings("unchecked") // for JDK 1.5 and above
public class HashMapSort {
public static void main(String[] args) {
Map m = new HashMap();
m.put("a", "some");
m.put("b", "random");
m.put("c", "words");
m.put("d", "to");
m.put("e", "be");
m.put("f", "sorted");
m.put("g", "by");
m.put("h", "value");
for (Iterator i = sortByValue(m).iterator(); i.hasNext(); ) {
String key = (String) i.next();
System.out.printf("key: %s, value: %s\n", key, m.get(key));
}
}

public static List sortByValue(final Map m) {
List keys = new ArrayList();
keys.addAll(m.keySet());
Collections.sort(keys, new Comparator() {
public int compare(Object o1, Object o2) {
Object v1 = m.get(o1);
Object v2 = m.get(o2);
if (v1 == null) {
return (v2 == null) ? 0 : 1;
}
else if (v1 instanceof Comparable) {
return ((Comparable) v1).compareTo(v2);
}
else {
return 0;
}
}
});
return keys;
}
}