/** Example from "Java 2 Certification" by Jamie Jaworski p187
    
    Using wait() and notify() to control access to a shared resource
*/

class Thread5 {
    public static void main(String[] args) {
        Resource resource = new Resource();
        Thread controller = new Thread(new Controller(resource));
        Thread[] user = new Thread[3];
        
        for(int i=0; i<user.length; i++) {
            user[i] = new Thread(new User(i,resource));
        }
        
        controller.start();
        
        for(int i=0; i<user.length; i++ ) {
            user[i].start();
        }
        
        boolean alive;
        
        out: do {
            alive = false;
            for( int i=0; i<user.length; i++ ) {
                alive |= user[i].isAlive();                
            }
            Thread.currentThread().yield();
        } while(alive);
        controller.interrupt();
    }
}

class Resource {
    boolean okToSend = false;
    
    public synchronized void displayOutput(int id, String[] msg ) {
        try {
                while(!okToSend) {
                    wait();
                }    
                okToSend = false;
                for( int i = 0; i<msg.length; i++) {
                    Thread.currentThread().sleep((long)1000);
                    System.out.println(id + ": " + msg[i] );
                }
        } catch(InterruptedException e) {}
    }
    
    public synchronized void allowOutput() {
        okToSend = true;
        notify();
    }
}

class Controller implements Runnable {
    Resource resource;
    
    public Controller(Resource resource) {
        this.resource = resource;
    }
    
    public void run() {
        try{
            while(true) {
                Thread.currentThread().sleep((long)10000);
                resource.allowOutput();
            }
        } catch(InterruptedException e){}
    }
}

class User implements Runnable {
    static String[] msg = { "Java", "is", "hot,", "aromatic,",
                            "and", "invigorating." };

    int id;
    Resource resource;
    
    public User(int id, Resource resource) {
        this.id = id;
        this.resource = resource;
    }    
    
    public void run() {
        resource.displayOutput(id, msg);
    }
   
}