objectbuffer.java

JAVA平台下优秀的CHART开源代码,可以实现类似EXCEL中的二维或三维的饼图/椎图功能.

/**
 * Copyright (C) 2003  Manfred Andres
 * 
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package freecs.util;

/**
 * FIFO-Buffer for objects whicht automatically removes Objects retrieved via
 * get(). Programmers have to verify if value has bin put to this ObjectBuffer.
 * If buffer is full, put-method returns false, on success it returns true.
 */
public class ObjectBuffer {
   private Object elements[];
   private int    nextAdd;
   private int    nextRemove;
   private int    capacity;
   private int    counter=0;

   private boolean isEmpty,
                   isFull;

   public ObjectBuffer (int cap) {
      if (cap < 1)
         this.capacity = 1;
      else
         this.capacity = cap;
      this.nextAdd=0;
      this.nextRemove=0;
      this.isEmpty = true;
      elements = new Object[capacity];
   }

   public int size () {
      return counter;
   }

   public int capacity () {
      return capacity;
   }

   public boolean isEmpty () {
      return isEmpty;
   }

   public boolean isFull () {
      return isFull;
   }

   public boolean put (Object o) {
      if (this.isFull ()) return false;
      elements[nextAdd] = o;
      nextAdd++;
      isEmpty = false;
      if (nextAdd >= capacity)
         nextAdd = 0;
      if (nextAdd == nextRemove)
         isFull = true;
      counter++;
      return true;
   }
	
	public boolean contains (Object o) {
		for (int i = 0, j=nextRemove; i < capacity; i++, j++) {
			if (j >= capacity) j = 0;
			if (elements[j].equals (o)) return true;
		}
		return false;
	}

   public Object get () {
      if (this.isEmpty ()) return null;
      return elements[nextRemove];
   }

   public Object pop () {
      if (this.isEmpty ()) return null;
      Object retObj = elements[nextRemove];
      elements[nextRemove]=null;
      nextRemove++;
      isFull = false;
      if (nextRemove >= capacity)
         nextRemove = 0;
      if (nextRemove == nextAdd)
         isEmpty = true;
      counter--;
      return (retObj);
   }

}