Question

I have this problem and I can’t seem to find on the Internet for a solution. I have posted a similar link here, http://www.coderanch.com/t/581517/java/java/cast-superclass-subclass#2645691

class Example implements Runnable {
       String ID;

       public Example (String ID) {
            this.ID = ID;
       }
       public void run() {
     // Code to do something.
   }
}

I am using a ScheduledThreadPoolExecutor class. Under that class, there is this method called getQueue. However the getQueue return a BlockingQueue of Runnable interface.
Is there a way to get back an Example class from a Blocking queue of Runnable interface?

Answer 1

Are you inserting new tasks into the queue using the schedule method of ScheduledThreadPoolExecutor?
Are these tasks instaces of the Example class?

If so, then when obtaining a new “Runnable” you can cast it to Example by:

Runnable r = getRunnableFromQueue();
Example e = (Example) r;

Depending on the flow of your program it may be a good idea to verify that the types match before casting (for example using instanceof).

Hope it helps.