Iterate enum values using java generics

Question

I\'m trying to find a way to iterate through an enum\'s values while using generics. Not sure how to do this or if it is possible.

The following code illustrates

Answer 1

If you declare Filter as

public class Filter

then

import java.util.Iterator;

public enum TimePeriod implements Iterable {
    ALL("All"),
    FUTURE("Future"),
    NEXT7DAYS("Next 7 Days"),
    NEXT14DAYS("Next 14 Days"),
    NEXT30DAYS("Next 30 Days"),
    PAST("Past"),
    LAST7DAYS("Last 7 Days"),
    LAST14DAYS("Last 14 Days"),
    LAST30DAYS("Last 30 Days");

    private final String name;

    private TimePeriod(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return name;
    }

    public Iterator iterator() {
        return new Iterator() {

            private int index;

            @Override
            public boolean hasNext() {
                return index < LAST30DAYS.ordinal();
            }

            @Override
            public TimePeriod next() {
                switch(index++) {
                    case    0   : return        ALL;
                    case    1   : return        FUTURE;
                    case    2   : return        NEXT7DAYS;
                    case    3   : return        NEXT14DAYS;
                    case    4   : return        NEXT30DAYS;
                    case    5   : return        PAST;
                    case    6   : return        LAST7DAYS;
                    case    7   : return        LAST14DAYS;
                    case    8   : return        LAST30DAYS;
                    default: throw new IllegalStateException();
                }
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }
}

And usage is quite easy:

public class Filter {
    private List availableOptions = new ArrayList();
    private T selectedOption;

    public Filter(T selectedOption) {
        this.selectedOption = selectedOption;
        Iterator it = selectedOption.iterator();
        while(it.hasNext()) {
            availableOptions.add(it.next());
        }
    }
}