Issues using "synchronized".

From:
frick.jeremiah@gmail.com
Newsgroups:
comp.lang.java.help
Date:
22 May 2006 11:26:49 -0700
Message-ID:
<1148322409.606827.77250@u72g2000cwu.googlegroups.com>
Hello everyone,

I'm running the following code:

public static void main( String[] argv ) {
    {
        syncClass aSyncClass = new syncClass();

        synchronized( aSyncClass ) {
            aSyncClass.begin();
            try {
                aSyncClass.wait();
            }
            catch( InterruptedException ie ) { }
         }
         System.out.println( (aSyncClass.getRes() ? "PASS" : "FAIL") );
    }

    // ******** //

    {
        syncClass aSyncClass = new syncClass();

        synchronized( aSyncClass ) {
            aSyncClass.begin();
            try {
                aSyncClass.wait();
            }
            catch( InterruptedException ie ) { }
         }
         System.out.println( (aSyncClass.getRes() ? "PASS" : "FAIL") );
    }

    System.exit( 0 );
}

The problem is this. The first time through the software executes as
expected and the wait completes as expected. The second time, though,
the task seems to hang while waiting.

If I put a delay loop between the two sections above (replace //
******** // with for( int j = 0; j < 10000000000000; j++ ); ), then the
second piece of software completes properly as well.

Since the class should go out of scope after the first sequence
completes and then is created new with the "new" keyword in the second
sequence I can't figure out why the delay loop is fixing the problem.
I'm wondering if there's something about the synchronized keyword that
I'm not aware of.

As a side note, I'm using JDK 1.3.1, due to some issues with some
software I'm using I cannot use a later JDK version.

Thanks,
Jeremy

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