如何从另一个线程访问线程的对象-Java

Question

I have a specific class which extends Thread. In my main i create a number of threads of that class. Each thread creates an object of class Hero (a class created by me).

Is there a way that one thread can access the object of the class Hero of another thread? I want to have a way to compare two objects of class Hero of two different threads, either having a method tha can have as arguments the two objects of the two different threads OR by having a way to pass values of the object of one thread to another thread.

Answer 1

What you could do is have it so that the Class that extends Thread accepts an object of Class Hero in its constructor, like so:

public class YourClass extends Thread{
     private Hero hero;

     YourClass(Hero hero){
          this.hero= hero;           
         }
 } 

This way you can create the object first and add it to an ArrayList, before passing the reference to the constructor of the new thread object:

ArrayList heroes= new ArrayList<Hero>();//this should be declared at the class level
Hero hero= new Hero();
heroes.add(hero);
YourClass thread= new YourClass(hero);

The ArrayList of Hero objects is now available to all your threads, and you can write a method which iterates through it to find the object you are looking for. How you do this is largely down to what it is exactly you want to do.

Answer 2

So... as others have said you can just put all your Hero objects in a static list, dictionary or other structure that everyone can access.

BUT its sounds to me like what you are trying to do actually is create Active Objects http://en.wikipedia.org/wiki/Active_object

When you have Active objects, each Active Object has its own thread that is tightly wound around its own processing loop. That loop is fed by a queue of "messages" that come in from other objects.

SO each object stores a reference to other objects it wants to talk to, not a reference to the threads. The threads are hidden inside the object. Each object only exposes one method to other objects -- "QueueMessage", which puts messages for processing on that queue.

That queue must be implemented as a thread-safe data structure. The easiest way to do that in Java is with a ConcurrentLinkedQueue

http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentLinkedQueue.html