Question

I have a Thread sub-class called XmlProcessor that needs to accept some list or array of Strings to process. I need this list to be completely private to each thread, so that it isn’t modified in any way by other threads. What is my best option?

Thanks,
Jared

Answer 1

Based on Jareds comment it seems you have something that looks like this.

public class MyClass extends Runnable{
   static ThreadLocal<List<String>> listBonds = new ThreadLocal<List<String>>();

   public MyClass (List<String> list){
        listBonds.set(list);
   }
   public void run(){
      listBonds.get(); // it returns null here?
   }

}

If my assumption is true then the reason listBonds.get() is null is because a different thread is accessing listBonds when you invoke set to when you invoke get

Image this

Thread 1:
  Thread myClass = new Thread(new MyClass(someList));
    listBonds.set(someList);
  myClass.start(); 
Thread 2: (MyClass)
  listBonds.get() --- A new thread is requesting the threadlocal variable and hence its null

If this is the case then the Runnable instance will be inherently thread-local/thread-safe and then you can have the List be an instance variable of the Runnable