Source Code : A multithreaded queue used for implementing producer-consumer style threading patterns

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A multithreaded queue used for implementing producer-consumer style threading patterns

  
/*
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import java.util.Stack;

/**
 * A multithreaded queue used for 
 * implementing producer-consumer style threading patterns.
 * Multiple threads can wait for runnable objects being added
 * to the queue while other threads add to the queue.
 */
public class Queue {

    private Stack tasks = new Stack();
    private long defaultTimeout = 100;

    public Queue() {
    }

    /**
     * Returns the current number of runnable objects in the queue
     */
    public synchronized int size() {
        return tasks.size();
    }

    /** 
     * adds a runnable object to the end of the queue.
     * At least one thread will be notified.
     */
    public synchronized void add(Object runnable) {
        tasks.push(runnable);
        notifyAll();
    }

    /** 
     * Removes the first runnable object from the queue, blocking until one is available.
     */
    public synchronized Object remove() {
        while (true) {
            Object runnable = removeNoWait();
            if ( runnable != null ) {
                return runnable;
            }
            try {
                wait( defaultTimeout );
            }
            catch (InterruptedException e) {
                e.printStackTrace();
              
            }
        }
    }

    /**
     * Removes the first runnable object from the queue without blocking.
     * This method will return immediately with an item from the queue or null.
     * @return the first runnable object removed from the queue or null if the
     * queue is empty
     */
    public synchronized Object removeNoWait() {
        if ( ! tasks.empty() ) {
            return tasks.pop();
        } else {
            return null;
        }
    }

}

   
    
  

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