Java泛型问题：类“不在类型变量的范围内”错误。 [英] Java generics issue: Class "not within bounds of type-variable" error.

问题描述

  public interface Keyable< T>< p> {public String getKey（）;} 
 
 public interface DataElement extends Comparable< Keyable< DataElement>>，< Keyable< DataElement> ;, Serializable {...} 
 public class CourseEdition DataElement { ...} 
 
 
 public interface SearchTree< K extends Comparable< Keyable< K>> &安培;可设置关键点< K>>扩展Serializable {...} 
 public class MySearchTree实现SearchTree< Course> {
 ... 
私人课程节点{
公开课程资料; 
公共节点离开; 
公共节点权利; 
 ... 
} 
} 
  

试图使用MySearchTree声明中的课程类，我收到一个类型参数错误，指出课程不在类型变量K的范围内。我花了大量的时间试图找出课程可能缺乏的一些特点，使其不适合帐单，但空了。

任何想法？ MySearchTree K

解决方案基础类型的$ c> 课程。因此 K 必须扩展可比较<可锁定<课程>> &安培;可设置关键点<课程和GT; 。但它没有，它扩展了 Comparable< Keyable< DataElement>> &安培; Keyable< DataElement> 。

我想 DataElement 应该类似于 Comparable 或 Enum 。

  public interface Keyable< T> {public String getKey（）;} 
 
 public interface DataElement< THIS extends DataElement< THIS>>可扩展<可关联< THIS>>，可键< THIS>，可序列化{...} 
公共类课程实现DataElement< Course> {...} 
 
 
 public interface SearchTree< K extends Comparable< Keyable< K>> &安培;可设置关键点< K>>扩展Serializable {...} 
 public class MySearchTree实现SearchTree< Course> {
  

I'm working on a project for class that involves generics.

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;
        ...
    }
}

When trying to use the Course class within the declaration of MySearchTree, I receive a type argument error stating that "Course is not within the bounds of type-variable K". I spent a good amount of time trying to figure out what attributes Course might be lacking to make it not fit the bill, but came up empty.

Any ideas?

解决方案

In MySearchTree the K of the base type is Course. So K must "extend" Comparable<Keyable<Course>> & Keyable<Course>. But it doesn't, it extends Comparable<Keyable<DataElement>> & Keyable<DataElement>.

I guess DataElement should be generified in a similar manner to Comparable or 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> {

这篇关于Java泛型问题：类“不在类型变量的范围内”错误。的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！