Some syntax problems (I guess)

Question

Hi, I'm having problem with the first constructor in this simplified example code... I want to create a "default" Comparator. I'm not quite sure how to do this.
public class MyClass<E> {
    private Comparator<E> comp;
    public MyClass() {
        MyClass(new ComparableComparatorBridge());
    public Myclass(Comparator<E> comp) {
        this.comp = comp;
    private class ComparableComparatorBridge<E extends Comparable> implements Comparator<E> {
        public int compare(E o1, E o2) {
            return ((Comparable)o1).compareTo(o2);
}

Answer 1

Event if you fix the syntax problems, following the advice of the other posters, you'll have a semantic problem:
MyClass<E> is parameterized with an unbounded type parameter.
You cannot assume that E implements Comparable<E>.
What you'd really need is a parameterizd constructor like this (won't compile):public <C extends E & Comparable<E>> MyClass() {
this(new ComparableComparatorBridge<C>());
}Unfortunately, this isn't valid Java. I see two possibilities:
1. Derive from MyClass and introduce the additional bound on the type parameter of the subclass. Then you can create a default-constructor using the ComparableComparatorBridge in that subclass.
2. Add a static factory function to MyClass, like this:
public class MyClass<E> {
    private final Comparator<E> comp;
    public MyClass(Comparator<E> comp) {
        this.comp = comp;
    public static <E extends Comparable<E>> MyClass<E> defaultComparable() {
        return new MyClass<E>(new ComparableComparatorBridge<E>());
    private static class ComparableComparatorBridge<E extends Comparable<E>> implements Comparator<E> {
        public int compare(E o1, E o2) {
            return o1.compareTo(o2);
}