Java“类型参数X不在其范围内；应该实现Comparable<X> &quot; (LocalDateTime 作为地图中的键)

Question

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

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

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;

I am getting the error Type parameter 'java.time.LocalDateTime' is not within its bound; should implement 'java.lang.Comparable<java.time.LocalDateTime>' Type parameter 'java.time.LocalDateTime' is not within its bound; should implement 'java.lang.Comparable<java.time.LocalDateTime>' .

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.

Any ideas?

Answer 1

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

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

Should be something like

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