Re: Working with threads. Example from java docs

From:
"danharrisandrews@gmail.com" <danharrisandrews@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
15 Aug 2006 11:56:22 -0700
Message-ID:
<1155668182.069786.248810@74g2000cwt.googlegroups.com>
Hi Progzmaster,

Try this:

public static void one() {
    i++;
    Thread.yield();
    j++;
}

Also this line "if ( this.interrupted() )" would b better if written
like this "if ( Thread.interrupted() )" since interrupted is a static
method.

Cheers,

Dan Andrews

- - - - - - - - - - - - - - - - - - - - - - - -
Ansir Development Limited www.ansir.ca
- - - - - - - - - - - - - - - - - - - - - - - -

Progzmaster wrote:

Hello there I am learing java like everybody here and I ecounter a small
problem that I am unable to solve.
This is the link to Java lang. spec. "volatile fields"
http://java.sun.com/docs/books/jls/third_edition/html/classes.html#8.3.1.4

There is a paragraph:
-------------------------------------------------------------------------=

-------------------------------------------

If, in the following example, one thread repeatedly calls the method one
(but no more than Integer.MAX_VALUE times in all), and another thread
repeatedly calls the method two:
class Test {
    static int i = 0, j = 0;
    static void one() { i++; j++; }
    static void two() {
        System.out.println("i=" + i + " j=" + j);
    }
}then method two could occasionally print a value for j that is greater t=

han

the value of i,
because the example includes no synchronization and, under the rules
explained in =A717,
the shared values of i and j might be updated out of order.
-------------------------------------------------------------------------=

----------------------------------------------

I tryied to write a simple program that is based on the above example so
that I can see different values of i and j.
I wrote one but unfortunatelly every time program runs each line shows the
same values for i and j.
Can you help me and fix my code or write another similar program that will
be doing such a thing
 so I can belive that it could happen - ( method two could occasionally
print a value for j that is greater than the value of i )

This is my code:
-------------------------------------------------------------------------=

--------------------------

class Test
{
    static int i=0, j=0;
    public static void one() { i++; j++; }
    public static void two()
    {
        System.out.println( "i=" + i + " j=" + j );
    }
}

class T1 extends java.lang.Thread
{
    public T1()
    {
        super();
        start();
    }

    public void run( )
    {
        while( true )
        {
            Test.one();
            if ( this.interrupted() ) return;
            yield();
        }
    }
}

class T2 extends java.lang.Thread
{
    public T2()
    {
        super();
        start();
    }

    public void run( )
    {
        while( true )
        {
            Test.two();
            if ( this.interrupted() ) return;
            yield();
        }
    }
}

public class Ex01
{
    public static void main( java.lang.String [] args )
    throws java.lang.InterruptedException
    {
        T2 t2 = new T2( );
        T1 t1 = new T1( );
        Thread.sleep(2000);
        t1.interrupt();
        t2.interrupt();
    }
}

-------------------------------------------------------------------------
 
Thank you
Progzmaster

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