source: trunk/gcc/libjava/testsuite/libjava.lang/TLtest.java

class TLtest extends Thread {

    public static void main (String [] args) {
        Data d = new Data ();
        new ThreadTest (d, "A").start ();
        new ThreadTest (d, "B").start ();
    }
}

class Data {

    private static ThreadLocal owner = new ThreadLocal () {
            public Object initialValue () { return ("0"); }
        };
    /* A thread will call `set' to set a value it wants an instance
       of Data to associate with it and only it. */
    synchronized public void set (String v){owner.set (v);}
    /* A thread will call `get' to get a value it wants an instance
       of Data to associate with it and only it. */
    synchronized public String get (){return (String)owner.get();}
}

class ThreadTest extends Thread {

    public Data d;

    ThreadTest (Data d, String name) {
        super (name);
        this.d = d;
    }

    public void run () {

        int value = 0;
        int ref = 0;

        for (int i = 0; i < 20; i++) {

            int rand = (int)(Math.random ()*20);

            /* Read `value', ref is kept for comparison */
            value = Integer.parseInt (d.get());
            
            /* change `value' and ref by a random number, store `value'. */
            value += rand; ref += rand;
            d.set (Integer.toString (value));

            try {
                sleep((int)(Math.random() * 500));
            } catch (InterruptedException e) {}
        }

        /* If a thread didn't have private value to attach to the
           instance of Data, results wouldn't be the same */
        if (ref == value)
            System.out.println ("test OK.");
        else
            System.out.println ("test failed.");
    }
}