Pass parameter to Call method in Java.util.Concurrent

Question

i am new to the high level Java.util.Concurrent package , what i am trying to do is read multiple text files at the same time using a thread pool. I need a way to pass the file name as an argument to my implementation of the call method .

Something like this :

public String call (String param)

If there is another way to achieve this i will appreciate your help.

Side comment: what you are doing is I/O bound rather than CPU bound and using multiple threads is unlikely to improve performance. It is actually probably going to be detrimental. — assylias, Jul 21 '12 at 16:52
each thread will carry much more CPU processing than just reading files — user1203861, Jul 21 '12 at 17:08
What you want is basically a function. Java cannot easily model functions as first-class citizens, at least syntactically. Languages that have better support for functional programming may be of interest. — Jed Wesley-Smith, Jul 22 '12 at 07:22

score 6 · Accepted Answer · edited Jul 21 '12 at 17:20

When implementing the Runnable interface, add your parameter as a member of the class. And add an initialization of this member in the constructor. Than use it from the run method.

For example:

class ConcurrentFileReader implements Runnable{
   String fileName;

   public ConcurrentFileReader(String fileName){ 
       this.fileName = fileName; 
   }

   public void run(){
       File f = new File(fileName);
      // whatever
   }
}

This pattern is known as a "Method Object"

Pass parameter to Call method in Java.util.Concurrent

1 Answers1