Java：如何实现私有抽象方法？
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Java: how to implement private abstract methods?
提问by elsni
Is it possible to define a private abstract class in Java? How would a Java developer write a construct like below?
是否可以在 Java 中定义私有抽象类？Java 开发人员将如何编写如下所示的构造？
public abstract class MyCommand {
public void execute()
{
if (areRequirementsFulfilled())
{
executeInternal();
}
}
private abstract void executeInternal();
private abstract boolean areRequirementsFulfilled();
}
采纳答案by Colin Hebert
You can't have private abstractmethods in Java.
private abstract在 Java 中不能有方法。
When a method is private, the sub classes can't access it, hence they can't override it.
当一个方法是 时private，子类不能访问它，因此它们不能覆盖它。
If you want a similar behavior you'll need protected abstractmethod.
如果您想要类似的行为，则需要protected abstract方法。
It is a compile-time error if a method declaration that contains the keyword
abstractalso contains any one of the keywordsprivate,static,final,native,strictfp, orsynchronized.
如果包含关键字的方法声明
abstract也包含关键字private,static,final,native,strictfp, or中的任何一个，则会出现编译时错误synchronized。
And
和
It would be impossible for a subclass to implement a
private abstractmethod, becauseprivatemethods are not inherited by subclasses; therefore such a method could never be used.
子类不可能实现一个
private abstract方法，因为private方法不是由子类继承的；因此这种方法永远无法使用。
Resources :
资源 ：
回答by Roland Illig
That would be protectedinstead of private. It means that only classes that extend MyCommandhave access to the two methods. (So do all classes from the same package, but that's a minor point.)
那将protected代替private. 这意味着只有扩展的类MyCommand才能访问这两个方法。（所有类都来自同一个包，但这是一个小问题。）
