Java 8 Distinct by property

Question

In Java 8 how can I filter a collection using the Stream API by checking the distinctness of a property of each object?

For example I have a list of

Answer 1

In my case I needed to control what was the previous element. I then created a stateful Predicate where I controled if the previous element was different from the current element, in that case I kept it.

public List fetchLogById(Long id) {
    return this.findLogById(id).stream()
        .filter(new LogPredicate())
        .collect(Collectors.toList());
}

public class LogPredicate implements Predicate {

    private Log previous;

    public boolean test(Log atual) {
        boolean isDifferent = previouws == null || verifyIfDifferentLog(current, previous);

        if (isDifferent) {
            previous = current;
        }
        return isDifferent;
    }

    private boolean verifyIfDifferentLog(Log current, Log previous) {
        return !current.getId().equals(previous.getId());
    }

}