Java中的树状数据结构

Question

I want to implement a tree like data structure in java for activity objects, where nodes can be shared between two parents. I want to build a hierarchy of activities, where one activity can be contained by multiple activities. How can I do it? Or should I use some other data structure and how?

Answer 1

Something like this should work:

public class Activity {

    private Activity parent1;
    private Activity parent2;
    private List<Activity> children;

    // other fields, getters, setters, methods, etc    

}

Answer 2

To decide on the design, it is of key importance to know how you need to navigate your structure. If only top-down, all you need is for an Activity to contain a list of its children. How you ensure that at most two activities own a certain activity is another thing. If you need to ensure that, then you'll probably need parent refs in an activity.