我试图用帮助器方法编写一些自定义异常来设置这样的变量:
public class KeyException extends RuntimeException { protected String Id; protected KeyException(String message) { super(message); } protected KeyException(String message, Throwable cause) { super(message, cause); } public String getId() { return keyId; } public KeyException withId(final String Id) { this.Id = Id; return this; } }
但是,在我的派生类中,我不能使用“withId”方法,因为它只返回基类 – 无论如何返回“this”指针而不必覆盖每个派生类中的方法?
is there anyway to return the “this” pointer without having to override the method in every single derived class?
是的,请看下面的选项1.
您可以通过以下几种方式执行此操作:
>将结果转换为派生类
>在子类中重写它
>将返回类型更改为void.由于您在对象上调用方法,因此您已经有了指向它的指针.
翻译自:https://stackoverflow.com/questions/18204190/java-abstract-classes-returning-this-pointer-for-derived-classes