1 class TLtest extends Thread {
2 
main(String [] args)3     public static void main (String [] args) {
4 	Data d = new Data ();
5 	new ThreadTest (d, "A").start ();
6 	new ThreadTest (d, "B").start ();
7     }
8 }
9 
10 class Data {
11 
12     private static ThreadLocal owner = new ThreadLocal () {
13 	    public Object initialValue () { return ("0"); }
14 	};
15     /* A thread will call `set' to set a value it wants an instance
16        of Data to associate with it and only it. */
set(String v)17     synchronized public void set (String v){owner.set (v);}
18     /* A thread will call `get' to get a value it wants an instance
19        of Data to associate with it and only it. */
get()20     synchronized public String get (){return (String)owner.get();}
21 }
22 
23 class ThreadTest extends Thread {
24 
25     public Data d;
26 
ThreadTest(Data d, String name)27     ThreadTest (Data d, String name) {
28 	super (name);
29 	this.d = d;
30     }
31 
run()32     public void run () {
33 
34 	int value = 0;
35 	int ref = 0;
36 
37 	for (int i = 0; i < 20; i++) {
38 
39 	    int rand = (int)(Math.random ()*20);
40 
41 	    /* Read `value', ref is kept for comparison */
42 	    value = Integer.parseInt (d.get());
43 
44 	    /* change `value' and ref by a random number, store `value'. */
45 	    value += rand; ref += rand;
46 	    d.set (Integer.toString (value));
47 
48 	    try {
49 		sleep((int)((Math.random() * 20)));
50 	    } catch (InterruptedException e) {}
51 	}
52 
53 	/* If a thread didn't have private value to attach to the
54 	   instance of Data, results wouldn't be the same */
55 	if (ref == value)
56 	    System.out.println ("test OK.");
57 	else
58 	    System.out.println ("test failed.");
59     }
60 }
61