ThreadLocalStack.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2006, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.jpa.util;

import java.util.ArrayList;
import java.util.List;

/**
 * Comment
 *
 * @author <a href="mailto:bill@jboss.org">Bill Burke</a>
 * @version $Revision$
 */
public class ThreadLocalStack<T>
{
   private ThreadLocal<ArrayList<T>> stack = new ThreadLocal<ArrayList<T>>();

   public void push(T obj)
   {
      ArrayList<T> list = stack.get();
      if (list == null)
      {
         list = new ArrayList<T>(1);
         stack.set(list);
      }
      list.add(obj);
   }

   public T pop()
   {
      ArrayList<T> list = stack.get();
      if (list == null)
      {
         return null;
      }
      T rtn = list.remove(list.size() - 1);
      if (list.size() == 0)
      {
         stack.set(null);
         list.clear();
      }
      return rtn;
   }

   public T get()
   {
      ArrayList<T> list = (ArrayList<T>)stack.get();
      if (list == null)
      {
         return null;
      }
      return list.get(list.size() - 1);
   }

   public List<T> getList()
   {
      return stack.get();     
   }
}