Java:捕获块可以是多态的吗? [英] Java: Can catch blocks be polymorphic?

问题描述

在我要参加重复考试的论文中，我被问到捕获块可以是多态的吗?".

In a paper I'm going over for a repeat exam, I'm asked "Can catch blocks be polymorphic?".

如果为true，则对多个catch块进行多态调用对我来说没有任何意义.如果catch块不能命名并且仅在其方法头中包含参数，那是否是多态性?

If true, it doesn't make sense to me to call multiple catch blocks polymorphic. Is it polymorphism if catch blocks cannot be named and only contain parameters in their method header?

例如:

try {

//...

} catch (FileNotFoundException e) {
    System.err.println("FileNotFoundException: " + e.getMessage());
    throw new SampleException(e);

} catch (IOException e) {
    System.err.println("Caught IOException: " + e.getMessage());
}

在这两个catch块是多态的吗?

In this, are these two catch blocks polymorphic?

推荐答案

您发布的示例应描述为超载.与重载唯一不同的是 readability 要求，即子类出现在其超类之前.

The example you posted should be described as overloading. The only thing different from overloading is a readability requirement that subclasses appears before its superclass.

语句多形抓块"需要一些体操来解析.

The statement "Polymorphic catch blocks" requires a bit of gymnastics to parse.

完成上述体操后，我将其解释为

After completing said gymnastics I would interpret it as

• 一个catch块，它根据要捕获的对象的类型提供不同的实现.

类似于

try{


} catchwith ( catchHandlerObject );

并且catchHandlerObject是多态的. IE.根据catchHandlerObject的(运行时)类型不同地处理相同的异常.

And catchHandlerObject is polymorphic. I.e. handles the same exception differently depending on the (runtime) type of catchHandlerObject.

是

class C{
   public void m(Object o){ .... };
}

m(Object o)是多态的吗?我要说的共识是，不必在此描述中包含多态性.呼叫m( stringObject ).并不表示多态性.

Is m(Object o) polymorphic? I would say that the consensus is that it is unnecessary to include polymorphism in to this description. A call m( stringObject ). is not indicative of polymorphism.

我和以前的海报相反，说不.多态不是标记这种情况的正确方法.多态性不是描述正在发生的事情的正确方法.

I go contrary to the previous posters an say no. Polymorphic is not the proper way to label this situation. Polymorphism is not the proper way to describe what is happening.

我也真的认为您应该与您的助教或您的教授仔细检查.问题经常发生，包括从拼写到完全脱心的经历等错误.

I also really think you should double check this with your TA or your professor. It happens regularly that questions include mistakes ranging from spelling to completely out of mind experiences.

如 yshavit 所述，重载表示编译时绑定.捕获块必须在运行时解决.我不知所措，但是找到了一个比重载更好的术语.

As yshavit noted, overloading indicates a compile time binding. The catch-block is by necessity resolved at runtime. I'm at a loss finding a better term than overloading though.

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