Java“类型参数X不在其范围之内；应该实现Comparable X.(LocalDateTime作为地图中的键) [英] Java "Type parameter X is not within its bound; should implement Comparable<X>" (LocalDateTime as key in map)

问题描述

我已经实现了自己的地图，称为AVLTreeMap.这是课程签名.

I have implemented my own Map called AVLTreeMap. Here is the class signature.

public class AVLTreeMap<K extends Comparable<K>, V>

如您所见，我在此地图中使用的是可比较的键.问题是我想使用 LocalDateTime 类型的键实例化地图.

As you can see, I am using comparable keys in this map. The problem is that I want to instantiate a map with a LocalDateTime type key.

private AVLTreeMap<LocalDateTime, CallRecord> callRecords;

我收到错误 Type参数'java.time.LocalDateTime'不在其范围内；应该实现"java.lang.Comparable< java.time.LocalDateTime>" .

据我所知，LocalDateTime实现了 Comparable< ChronoLocalDateTime<?>> ，在这一点上，我对于如何使用创建地图非常困惑LocalDateTime 键集.

As far as I can tell, LocalDateTime implements Comparable<ChronoLocalDateTime<?>> and at this point, I am pretty confused as to how I can create my map with a LocalDateTime key set.

有什么想法吗?

推荐答案

您对可比较的通用签名有点差，

Your generic signature for a Comparable is a little off, this

public class AVLTreeMap<K extends Comparable<K>, V>

应该是

public class AVLTreeMap<K extends Comparable<? super K>, V>

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