调用存在于子类中但不存在于父类中的方法 [英] Calling method that exists in child classes but not in parent class
问题描述
public class Parent {
....
}
public class Child1 extends Parent {
....
public void foo() {
....
}
}
public class Child2 extends Parent {
....
public void foo() {
....
}
}
这里方法 foo()
只存在于Child类中,不能添加到Parent类(甚至不是抽象方法)。在这种情况下,我想在 obj
上调用 foo()
方法,这是 Parent
类的引用然后我需要使用 intanceof
多个 if..else
我想要的避免。
Here method foo()
only exists in the Child classes and CAN NOT be added to the Parent class (not even abstract method). In this situation when I want to call the foo()
method on obj
which is Parent
class's reference then I need to use intanceof
with multiple if..else
which I want to avoid.
Parent obj = ...// Object of one of the child classes
obj.foo();
编辑:我需要使用的类型obj
仅限 Parent
。否则我将无法调用父类中存在的obj上的方法。
I Need to use type of obj
as Parent
only. Else I will not be able to call methods on obj which exists in Parent class.
我的解决方案:我想的方法是用 foo()
方法定义一个接口说 FooInterface
并让所有子类实现它,然后我可以只输入 obj
到该接口并调用foo()方法,如下所示:
My Solution: The approach that I am thinking is to define an interface say FooInterface
with foo()
method and let all the child classes implement it, then I could just type cast the obj
to that interface and call foo() method like this:
if(obj instanceof FooInterface){
((FooInterface)obj).foo();
}
有更好的方法吗?或者对这个有什么改进?
Is there a better approach ? Or any improvement to this one?
推荐答案
我最终采取的方法是定义一个接口说 FooInterface
使用 foo()
方法并让所有子类实现它,然后我可以输入obj到该接口并调用 foo()
这样的方法:
The approach that I am finally taking is to define an interface say FooInterface
with foo()
method and let all the child classes implement it, then I could just type cast the obj to that interface and call foo()
method like this:
Parent obj = ...// Object of one of the child classes
.....
if(obj instanceof FooInterface){
((FooInterface)obj).foo();
}
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