Abstract Object Comparison in Java

问题

I am implementing a heap for abstract objects. Now I was able to implement a stack as there are no comparisons required for a Stack. However the heap requires comparisons. So I have Object A, and Object B. I can ensure that the Object that are in the heap are of the same class, and that they can be ordered (that is the class has a compareTo function to know if A<B, A=B, or A>B). But if I use A.compareTo(B), I get a syntax error saying that compareTo is not defined for objects. I did some research and found that Object does not implement Comparable. How can I go about this problem. Thank you.

回答1:

What if all your objects were descendants of a common ancestor which do implement Comparable? So in that case you could use that type in your code not Object.

回答2:

Object does not implements comparable. You should crate MyObject which implements Comparable interface.

class MyObject implements Comparable<Object>{
    ...
    @Override
    public int compareTo(Object arg0) {
        //  custom logic
        return 0;
    }
}

回答3:

- Well you can make that class implement java.lang.Comparable Interface with Object as Type Parameter

public class Test implements Comparable<Object>{

    public int compareTo(Object o){

       // 

    }

}

来源：https://stackoverflow.com/questions/13305940/abstract-object-comparison-in-java