Application: gvSIG desktop » gvSIG raster

/* gvSIG. Geographic Information System of the Valencian Government

*

* Copyright (C) 2007-2008 Infrastructures and Transports Department

* of the Valencian Government (CIT)

* 

* This program is free software; you can redistribute it and/or

* modify it under the terms of the GNU General Public License

* as published by the Free Software Foundation; either version 2

* of the License, or (at your option) any later version.

* 

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

* GNU General Public License for more details.

* 

* You should have received a copy of the GNU General Public License

* along with this program; if not, write to the Free Software

* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 

* MA  02110-1301, USA.

* 

*/

package org.gvsig.raster.util;

import java.util.Vector;

/**

 * A simple FIFO queue class which causes the calling thread to wait if the

 * queue is empty and notifies threads that are waiting when it is not

 * empty.

 * 

 * @author Anil V (akv@eng.sun.com)

 */

public class Queue {

        private Vector<Object> vector = new Vector<Object>();

        /**

         * Put the object into the queue.

         * 

         * @param object

         *            the object to be appended to the queue.

         */

        public synchronized void put(Object object) {

                vector.addElement(object);

                notify();

        }

        /**

         * Pull the first object out of the queue. Wait if the queue is empty.

         */

        public synchronized Object pull() {

                while (isEmpty())

                        try {

                                wait();

                        } catch (InterruptedException ex) {

                        }

                        return get();

        }

        /**

         * Get the first object out of the queue. Return null if the queue is

         * empty.

         */

        public synchronized Object get() {

                Object object = peek();

                if (object != null)

                        vector.removeElementAt(0);

                return object;

        }

        /**

         * Peek to see if something is available.

         */

        public Object peek() {

                if (isEmpty())

                        return null;

                return vector.elementAt(0);

        }

        /**

         * Is the queue empty?

         */

        public boolean isEmpty() {

                return vector.isEmpty();

        }

        /**

         * How many elements are there in this queue?

         */

        public int size() {

                return vector.size();

        }

}