source: liacs/cvp/java/first/RWProblem.java@ 38

/*
 * Rick van der Zwet
 * 0433373
 * Java programming assigment 1.2
 * Licence: BSD
 * $Id: RWProblem.java 270 2007-10-13 13:45:29Z rick $
 */
import java.util.Random;


class ReadProcess extends Process
{
    public ReadProcess(int number, Database database)
    {
        super(number, database);
    }

    public void run ()
    {
        message("Started as READ");
        database.get_readlock();
        message("Read: " + database.read());
        sleep();
        database.release_writelock();
        message("Ended");
    }
}

class WriteProcess extends Process
{
    public WriteProcess(int number, Database database)
    {
        super(number, database);
    }

    public void run ()
    {
        message("Started as WRITE");
        database.get_writelock();
        database.write(Integer.toString(id));
        sleep();
        message("Wrote his Id");
        database.release_writelock();
        message("Ended");
    }
}

class Process extends Thread
{
    protected int id;
    protected Database database;

    Process (int number, Database d)
    {
        this.id = number;
        database = d;
    }

    protected void sleep ()
    {
        int sleeptime;
        sleeptime = (int) (Math.random () * 1000);
        try
        {
            Thread.sleep( sleeptime );
        }
        catch ( InterruptedException e) { }
    }

    protected void message (String text)
    {
        System.out.println("[" + id + "] " + text);
    }
}

public class RWProblem
{
    public static void main (String args[])
    {
        Database database;
        int N = 100; //processes
        int i; //loop counter
        Random write = new Random();

        database = new Database();
        Process [] process = new Process [N];

        for( i = 0; i < N; i++)
        {
            if (write.nextBoolean())
            {
                process[i] = new WriteProcess (i, database);
            }
            else {
                process[i] = new ReadProcess (i, database);
            }
            process[i].start();
        }
    }
}