What is the best way to filter a Java Collection?

Question

I want to filter a java.util.Collection based on a predicate.

Answer 1

Some really great great answers here. Me, I'd like to keep thins as simple and readable as possible:

public abstract class AbstractFilter {

    /**
     * Method that returns whether an item is to be included or not.
     * @param item an item from the given collection.
     * @return true if this item is to be included in the collection, false in case it has to be removed.
     */
    protected abstract boolean excludeItem(T item);

    public void filter(Collection collection) {
        if (CollectionUtils.isNotEmpty(collection)) {
            Iterator iterator = collection.iterator();
            while (iterator.hasNext()) {
                if (excludeItem(iterator.next())) {
                    iterator.remove();
                }
            }
        }
    }
}