Java泛型问题:类"不在类型变量的范围内"错误.

Question

我正在研究一个涉及泛型的课程.

public interface Keyable <T> {public String getKey();}

public interface DataElement extends Comparable<Keyable<DataElement>>, Keyable<DataElement>, Serializable {...}
public class Course implements DataElement {...}


public interface SearchTree<K extends Comparable<Keyable<K>> & Keyable<K>> extends Serializable {...}
public class MySearchTree implements SearchTree<Course> {
...
    private class Node {
        public Course data;
        public Node left;
        public Node right;
        ...
    }
}

当尝试在MySearchTree的声明中使用Course类时,我收到一个类型参数错误,指出"Course不在类型变量K的范围内".我花了很多时间试图弄清楚课程可能缺少什么属性使它不适合账单,但是空洞.

有任何想法吗？

Answer 1

在MySearchTree该K基本类型的是Course.所以K必须"延伸" Comparable<Keyable<Course>> & Keyable<Course>.但事实并非延伸Comparable<Keyable<DataElement>> & Keyable<DataElement>.

我想DataElement应该以类似的方式对泛型Comparable或Enum.

public interface Keyable <T> {public String getKey();}

public interface DataElement<THIS extends DataElement<THIS>> extends Comparable<Keyable<THIS>>, Keyable<THIS>, Serializable {...}
public class Course implements DataElement<Course> {...}


public interface SearchTree<K extends Comparable<Keyable<K>> & Keyable<K>> extends Serializable {...}
public class MySearchTree implements SearchTree<Course> {