collections - 比较 Java8 中的 Instant

Question

我有这个对象：

public class MatchEvent implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;


    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;


    private Instant dateReceived;

    public Instant getDateReceived() {
        return dateReceived;
    }


    public void setDateReceived(Instant dateReceived) {
        this.dateReceived = dateReceived;
    }

}

我想在收到日期之前订购它；

matchService
            .findAllByDay(today)
                .sorted(Comparator.comparing(MatchEvent::dateReceived))

但这似乎是不可能的，因为我遇到了编译错误：

Multiple markers at this line
    - The method comparing(Function<? super T,? extends U>) in the type Comparator is not applicable for the arguments 
     (MatchEvent::dateReceived)
    - The type MatchEvent does not define dateReceived(T) that is applicable here

标签： collectionsjava-8java-streamcomparatoricomparable

Answer 1

声明一个名为getDateReceived()inside的公共方法class MatchEvent，如下所示：

public Instant getDateReceived(){
    return dateReceived;
}

然后您可以将此方法用作方法参考，如下所示：

Comparator.comparing(MatchEvent::getDateReceived)