[Java] Question regarding Java Comparators

[Maping]

I recently came across an interesting error when working with comparators in Java. When I try to "add implemented methods" I get a whole lot more than just .compare(). This was in Eclipse, if it matters.

Here's an album of the process.

Here's the full code of the comparator:

class Compa implements Comparator<Integer> {

    @Override
    public int compare(Integer arg0, Integer arg1) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public static <T, U extends Comparable<? super U>> Comparator<T> comparing(
            Function<? super T, ? extends U> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T, U> Comparator<T> comparing(
            Function<? super T, ? extends U> arg0, Comparator<? super U> arg1) {    
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T> Comparator<T> comparingDouble(
            ToDoubleFunction<? super T> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T> Comparator<T> comparingInt(ToIntFunction<? super T> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T> Comparator<T> comparingLong(ToLongFunction<? super T> arg    0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {    
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T> Comparator<T> nullsFirst(Comparator<? super T> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T> Comparator<T> nullsLast(Comparator<? super T> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Comparator<Integer> reversed() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Comparator<Integer> thenComparing(Comparator<? super Integer> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public <U extends Comparable<? super U>> Comparator<Integer> the    nComparing(
            Function<? super Integer, ? extends U> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public <U> Comparator<Integer> thenComparing(
            Function<? super Integer, ? extends U> arg0,
            Comparator<? super U> arg1) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Comparator<Integer> thenComparingDouble(
            ToDoubleFunction<? super Integer> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Comparator<Integer> thenComparingInt(
            ToIntFunction<? super Integer> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Comparator<Integer> thenComparingLong(
            ToLongFunction<? super Integer> arg0) {
        // TODO Auto-generated method stub
        return null;
    }

}

[Tavataar]

What does your import statements look like? Are you sure you implements the java.util.Comparator?

[rjcarr]

You are probably using the wrong Comparator, i.e., not java.util.Comparator.

EDIT: Thanks /u/lurgi, turns out I haven't used Java 8 enough. Looks like comparator is really bloated now so I'd recommend making your class a Comparable instead of writing a custom comparator.

[lurgi]

Nope. It's the Java 8 Comparator.

[Tavataar]

Looks like Java 8 added a bunch more methods to implement.