root / trunk / extensions / extRasterTools-SE / src / org / gvsig / raster / util / Queue.java @ 20867
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| 1 | 20749 | nbrodin | /* gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana
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| 2 | *
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| 3 | * Copyright (C) 2007 IVER T.I. and Generalitat Valenciana.
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| 4 | *
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| 5 | * This program is free software; you can redistribute it and/or
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| 6 | * modify it under the terms of the GNU General Public License
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| 7 | * as published by the Free Software Foundation; either version 2
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| 8 | * of the License, or (at your option) any later version.
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| 9 | *
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| 10 | * This program is distributed in the hope that it will be useful,
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| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | * GNU General Public License for more details.
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| 14 | *
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| 15 | * You should have received a copy of the GNU General Public License
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| 16 | * along with this program; if not, write to the Free Software
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| 17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,USA.
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| 18 | */
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| 19 | package org.gvsig.raster.util; |
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| 20 | |||
| 21 | /*
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| 22 | * Created on 10-mar-2006
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| 23 | *
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| 24 | * gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana
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| 25 | *
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| 26 | * Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.
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| 27 | *
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| 28 | * This program is free software; you can redistribute it and/or
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| 29 | * modify it under the terms of the GNU General Public License
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| 30 | * as published by the Free Software Foundation; either version 2
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| 31 | * of the License, or (at your option) any later version.
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| 32 | *
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| 33 | * This program is distributed in the hope that it will be useful,
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| 34 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 35 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 36 | * GNU General Public License for more details.
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| 37 | *
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| 38 | * You should have received a copy of the GNU General Public License
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| 39 | * along with this program; if not, write to the Free Software
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| 40 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,USA.
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| 41 | *
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| 42 | * For more information, contact:
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| 43 | */
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| 44 | |||
| 45 | import java.util.Vector; |
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| 46 | |||
| 47 | /**
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| 48 | * A simple FIFO queue class which causes the calling thread to wait if the
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| 49 | * queue is empty and notifies threads that are waiting when it is not
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| 50 | * empty.
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| 51 | *
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| 52 | * @author Anil V (akv@eng.sun.com)
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| 53 | */
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| 54 | public class Queue { |
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| 55 | private Vector vector = new Vector(); |
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| 56 | |||
| 57 | /**
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| 58 | * Put the object into the queue.
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| 59 | *
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| 60 | * @param object
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| 61 | * the object to be appended to the queue.
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| 62 | */
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| 63 | public synchronized void put(Object object) { |
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| 64 | vector.addElement(object); |
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| 65 | notify(); |
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| 66 | } |
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| 67 | |||
| 68 | /**
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| 69 | * Pull the first object out of the queue. Wait if the queue is empty.
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| 70 | */
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| 71 | public synchronized Object pull() { |
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| 72 | while (isEmpty())
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| 73 | try {
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| 74 | wait(); |
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| 75 | } catch (InterruptedException ex) { |
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| 76 | } |
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| 77 | return get();
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| 78 | } |
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| 79 | |||
| 80 | /**
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| 81 | * Get the first object out of the queue. Return null if the queue is
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| 82 | * empty.
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| 83 | */
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| 84 | public synchronized Object get() { |
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| 85 | Object object = peek();
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| 86 | if (object != null) |
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| 87 | vector.removeElementAt(0);
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| 88 | return object;
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| 89 | } |
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| 90 | |||
| 91 | /**
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| 92 | * Peek to see if something is available.
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| 93 | */
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| 94 | public Object peek() { |
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| 95 | if (isEmpty())
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| 96 | return null; |
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| 97 | return vector.elementAt(0); |
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| 98 | } |
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| 99 | |||
| 100 | /**
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| 101 | * Is the queue empty?
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| 102 | */
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| 103 | public boolean isEmpty() { |
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| 104 | return vector.isEmpty();
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| 105 | } |
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| 106 | |||
| 107 | /**
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| 108 | * How many elements are there in this queue?
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| 109 | */
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| 110 | public int size() { |
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| 111 | return vector.size();
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| 112 | } |
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| 113 | } |