java - 在具有多个边界的类型参数上出现编译错误

Question

为什么我在 FuzzyWuzzyContainer 上遇到这个编译器错误？

Bound mismatch:The type FuzzyWuzzy is not a valid substitute for the bounded parameter <T extends Fuzzy & Comparable<T>> of the type FuzzyContainer

FuzzyWuzzy 实际上确实实现了有界泛型中定义的两个接口(interface)。

public interface Fuzzy
{
    boolean isFuzzy();
}

public class FuzzyWuzzy implements Fuzzy, Comparable<Fuzzy>
{
    public boolean isFuzzy() {return true;}
    public int compare(Fuzzy o) {return 0;)
}

public abstract class FuzzyContainer<T extends Fuzzy & Comparable<T>>
{
   :
}

public class FuzzyWuzzyContainer extends Fuzzycontainer<FuzzyWuzzy> // Error is here
{
}

Answer 1

问题是FuzzyWuzzy implements Comparable<Fuzzy> . FuzzyContainer期待两个T在FuzzyContainer<T extends Fuzzy & Comparable<T>>是同一类型。 FuzzyWuzzy工具 Fuzzy但它没有实现 Comparable<FuzzyWuzzy> .

尝试，FuzzyWuzzy implements Fuzzy, Comparable<FuzzyWuzzy>