java – 流映射以便查找最新密钥的值

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class Element implements Comparable<Element> {

    String abbreviation;
    LocalDateTime creationTime;

    public Element(String abbreviation,LocalDateTime creationTime) {
        this.abbreviation = abbreviation;
        this.creationTime = creationTime;
    }

    public String getAbbreviation() {
        return abbreviation;
    }

    public void setAbbreviation(String abbreviation) {
        this.abbreviation = abbreviation;
    }

    public LocalDateTime getCreationTime() {
        return creationTime;
    }

    public void setCreationTime(LocalDateTime creationTime) {
        this.creationTime = creationTime;
    }

    /*
     * (non-Javadoc)
     * 
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    @Override
    public int compareTo(Element otherElement) {
        return this.creationTime.compareTo(otherElement.getCreationTime());
    }

    @Override
    public String toString() {
        return "[" + abbreviation + "," + creationTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) + "]";
    }
}

请注意,Element不能实现Comparable< Element>只使用LocalDateTime的内置比较.

public enum Attributes {

    DONE,FIRST_REGISTRATION,SUBSEQUENT_REGISTRATION
}

我当前的方法是只能过滤keySet并找到最新的密钥,然后我用它来简单地获取新代码行中的值.我想知道是否可以在单个stream().filter(…)语句中：

Map<Element,Attributes> results = new TreeMap<>();

// filling the map with random elements and attributes

Element latestKey = results.keySet().stream().max(Element::compareTo).get();
Attributes latestValue = results.get(latestKey);

Can we get a value by filtering the keySet of a Map in a single stream() statement like

Attributes latestValue = results.keySet().stream()
                .max(Element::compareTo)
                // what can I use here?
                .somehowAccessTheValueOfMaxKey()
                .get()

？

附加信息
我不需要像null那样的默认值,因为只有在包含至少一个键值对时才会检查Map,这意味着至少会有一个最新的元素 – 属性对,一个是唯一的.