如何使用子类型？(How to use subtypes?

如何使用子类型？(How to use subtypes? - overriding and inheriting in Java)

我的Java代码存在问题。 我有四个（重要）类：

public class RDOutput extends OutputType public class RDAnalysis extends AnalysisProperties

现在我正在尝试在Analysis属性中创建一个方法：

public abstract void display(ArrayList<? extends OutputType> results);

主要问题列表，ArrayList中的对象将是OutputType的不同子类型。 在我的课程RDAnalysis中，我尝试进行特定的覆盖：

public void display(ArrayList<RDOutput> results) {

但是eclipse说：名称冲突：类型RDAnalysis的方法显示（ArrayList）与AnalysisProperties类型的显示（ArrayList？extends OutputType）具有相同的擦除但不覆盖它

我不熟悉Java技巧，我尝试在文档中搜索，但我找不到任何解决这个问题的方法。 我的问题是：我正在做的那种技巧（抽象的基本类型和最终函数中的扩展）可能在Java中（如果是的话，我该怎么做？）或者我必须做一些枚举来解决这个问题吗？

I've got problem in my code in Java. I have four(important) Classes:

public class RDOutput extends OutputType public class RDAnalysis extends AnalysisProperties

Now I'm trying to make a method in Analysis properties:

public abstract void display(ArrayList<? extends OutputType> results);

The main problem list, the objects in the ArrayList will be different subtypes of OutputType. In my class RDAnalysis I try to make specific overriding:

public void display(ArrayList<RDOutput> results) {

but eclipse says: Name clash: The method display(ArrayList) of type RDAnalysis has the same erasure as display(ArrayList? extends OutputType) of type AnalysisProperties but does not override it

I'm not familiar with Java tricks, I tried searching in documentation and I didn't find any solution to this problem. My question is: Is that trick that I'm doing (Basic type in abstract and Extended in final function) possible in Java (if yes, how can I do that?) or do I have to make some enum to solve this?

最满意答案

我建议你在你的类中引入泛型参数，并用它来参数化你的方法：

public abstract class A<T extends OutputType> { public abstract void display(ArrayList<T> results); } public class B extends A<RDOutput> { public void display(ArrayList<RDOutput> results) {} }

I suggest you to introduce generic parameter to your class and use it to parametrize your method:

public abstract class A<T extends OutputType> { public abstract void display(ArrayList<T> results); } public class B extends A<RDOutput> { public void display(ArrayList<RDOutput> results) {} }