调用超超类方法 [英] Calling super super class method

问题描述

假设我有三个班级 A、B 和 C.

• B 扩展了 A
• C 扩展了 B

都定义了一个 public void foo() 方法.

现在从 C 的 foo() 方法我想调用 A 的 foo() 方法(不是它的父 B 的方法，而是超超类 A 的方法).

我尝试了 super.super.foo();，但它的语法无效.我怎样才能做到这一点?

解决方案

你甚至不能使用反射.类似的东西

Class superSuperClass = this.getClass().getSuperclass().getSuperclass();superSuperClass.getMethod("foo").invoke(this);

会导致InvocationTargetException，因为即使你在superSuperClass上调用foo-Method，当你指定this"在调用.这是所有 Java 方法都是虚方法这一事实的结果.

看来您需要 B 类的帮助(例如，通过定义一个 superFoo(){ super.foo(); } 方法).

也就是说，如果您尝试这样的操作，它看起来像是一个设计问题，因此向我们提供一些背景信息会很有帮助:为什么您需要这样做?

Let's say I have three classes A, B and C.

• B extends A
• C extends B

All have a public void foo() method defined.

Now from C's foo() method I want to invoke A's foo() method (NOT its parent B's method but the super super class A's method).

I tried super.super.foo();, but it's invalid syntax. How can I achieve this?

解决方案

You can't even use reflection. Something like

Class superSuperClass = this.getClass().getSuperclass().getSuperclass();
superSuperClass.getMethod("foo").invoke(this);

would lead to an InvocationTargetException, because even if you call the foo-Method on the superSuperClass, it will still use C.foo() when you specify "this" in invoke. This is a consequence from the fact that all Java methods are virtual methods.

It seems you need help from the B class (e.g. by defining a superFoo(){ super.foo(); } method).

That said, it looks like a design problem if you try something like this, so it would be helpful to give us some background: Why you need to do this?

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