Declarations, Initialization, and Scoping - SCJP Sun Certified Programmer for Java Platform SE6 - page 160

Notice that the anonymous inner class has access to the fi eld x and also the final local
variable s . Study the code and try to determine its output.
1. public class AnonInner {
2. public int x = 10;
3.
4. public void printX() {
5. final String s = “x = “;
6. Thread t = new Thread() {
7. public void run() {
8. while(true) {
9. System.out.println(s + x);
10. }
11. }
12. };
13. t.start();
14. }
15.
16. public static void main(String [] args) {
17. new AnonInner().printX();
18. }
19.}
You might not be familiar with threads in Java, but invoking start on a Thread object
causes its run method to execute in a new thread of the process. Here is the sequence of
events that occurs within main :
1. A new outer object is instantiated on line 17 and its printX method on line 4 is
invoked.
2. An anonymous inner class that extends Thread is declared and instantiated on
lines 6 to 12.
3. The start method is invoked on this Thread object on line 13, which causes the run
method on line 7 to execute.
4. The run method contains an infinite loop and prints out “x=10” until the JVM is
terminated manually (press Ctrl+C in Windows).
Because the anonymous inner class does not have a name, the compiler assigns it a
number. When AnonInner is compiled, two bytecode fi les are generated: AnonInner.class
and AnonInner$1.class .