Glassfish example source code file (ArrayStack.java)

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Java - Glassfish tags/keywords

arraylist, arraystack, arraystack, current, current, e, e, emptystackexception, emptystackexception, object, util

The Glassfish ArrayStack.java source code

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 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
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 * permission notice:
 *
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
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package org.apache.tomcat.util.digester;

import java.util.ArrayList;
import java.util.EmptyStackException;

/**
 * <p>Imported copy of the ArrayStack class from
 * Commons Collections, which was the only direct dependency from Digester.</p>
 *
 * <p>WARNNG - This class is public solely to allow it to be
 * used from subpackages of <code>org.apache.tomcat.util.digester.
 * It should not be considered part of the public API of Commons Digester.
 * If you want to use such a class yourself, you should use the one from
 * Commons Collections directly.</p>
 *
 * <p>An implementation of the {@link java.util.Stack} API that is based on an
 * <code>ArrayList instead of a Vector, so it is not
 * synchronized to protect against multi-threaded access.  The implementation
 * is therefore operates faster in environments where you do not need to
 * worry about multiple thread contention.</p>
 *
 * <p>Unlike Stack, ArrayStack accepts null entries.
 * </p>
 *
 * @see java.util.Stack
 * @since Digester 1.6 (from Commons Collections 1.0)
 */
public class ArrayStack<E> extends ArrayList {

    /** Ensure serialization compatibility */    
    private static final long serialVersionUID = 2130079159931574599L;

    /**
     * Constructs a new empty <code>ArrayStack. The initial size
     * is controlled by <code>ArrayList and is currently 10.
     */
    public ArrayStack() {
        super();
    }

    /**
     * Constructs a new empty <code>ArrayStack with an initial size.
     * 
     * @param initialSize  the initial size to use
     * @throws IllegalArgumentException  if the specified initial size
     *  is negative
     */
    public ArrayStack(int initialSize) {
        super(initialSize);
    }

    /**
     * Return <code>true if this stack is currently empty.
     * <p>
     * This method exists for compatibility with <code>java.util.Stack.
     * New users of this class should use <code>isEmpty instead.
     * 
     * @return true if the stack is currently empty
     */
    public boolean empty() {
        return isEmpty();
    }

    /**
     * Returns the top item off of this stack without removing it.
     *
     * @return the top item on the stack
     * @throws EmptyStackException  if the stack is empty
     */
    public E peek() throws EmptyStackException {
        int n = size();
        if (n <= 0) {
            throw new EmptyStackException();
        } else {
            return get(n - 1);
        }
    }

    /**
     * Returns the n'th item down (zero-relative) from the top of this
     * stack without removing it.
     *
     * @param n  the number of items down to go
     * @return the n'th item on the stack, zero relative
     * @throws EmptyStackException  if there are not enough items on the
     *  stack to satisfy this request
     */
    public E peek(int n) throws EmptyStackException {
        int m = (size() - n) - 1;
        if (m < 0) {
            throw new EmptyStackException();
        } else {
            return get(m);
        }
    }

    /**
     * Pops the top item off of this stack and return it.
     *
     * @return the top item on the stack
     * @throws EmptyStackException  if the stack is empty
     */
    public E pop() throws EmptyStackException {
        int n = size();
        if (n <= 0) {
            throw new EmptyStackException();
        } else {
            return remove(n - 1);
        }
    }

    /**
     * Pushes a new item onto the top of this stack. The pushed item is also
     * returned. This is equivalent to calling <code>add.
     *
     * @param item  the item to be added
     * @return the item just pushed
     */
    public E push(E item) {
        add(item);
        return item;
    }


    /**
     * Returns the one-based position of the distance from the top that the
     * specified object exists on this stack, where the top-most element is
     * considered to be at distance <code>1.  If the object is not
     * present on the stack, return <code>-1 instead.  The
     * <code>equals() method is used to compare to the items
     * in this stack.
     *
     * @param object  the object to be searched for
     * @return the 1-based depth into the stack of the object, or -1 if not found
     */
    public int search(E object) {
        int i = size() - 1;        // Current index
        int n = 1;                 // Current distance
        while (i >= 0) {
            Object current = get(i);
            if ((object == null && current == null) ||
                (object != null && object.equals(current))) {
                return n;
            }
            i--;
            n++;
        }
        return -1;
    }


}