How to declare array elements volatile in Java?

Question

Is there a way to declare array elements volatile in Java? I.e.

volatile int[] a = new int[10];

declares the array reference volatile, but the array elements (e.g. a[1]) are still not volatile. So I'm looking for something like

volatile int[] a = new volatile int[10];

but it doesn't work that way. Is it possible at all?

Answer 1

use AtomicIntegerArray or AtomicLongArray

The AtomicIntegerArray class implements an int array whose individual fields can be accessed with volatile semantics, via the class's get() and set() methods. Calling arr.set(x, y) from one thread will then guarantee that another thread calling arr.get(x) will read the value y (until another value is read to position x).

http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/atomic/AtomicIntegerArray.html http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/atomic/AtomicLongArray.html http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/atomic/package-summary.html

Answer 2

No, you can't make array elements volatile. See also http://jeremymanson.blogspot.com/2009/06/volatile-arrays-in-java.html .