/*
* @(#)Stack.java 1.12 95/08/11
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package java.util;
/**
* A Last-In-First-Out(LIFO) stack of objects.
*
* @version 1.12, 11 Aug 1995
* @author Jonathan Payne
*/
public
class Stack extends Vector {
/**
* Pushes an item onto the stack.
* @param item the item to be pushed on.
*/
public Object push(Object item) {
addElement(item);
return item;
}
/**
* Pops an item off the stack.
* @exception EmptyStackException If the stack is empty.
*/
public Object pop() {
Object obj;
int len = size();
obj = peek();
removeElementAt(len - 1);
return obj;
}
/**
* Peeks at the top of the stack.
* @exception EmptyStackException If the stack is empty.
*/
public Object peek() {
int len = size();
if (len == 0)
throw new EmptyStackException();
return elementAt(len - 1);
}
/**
* Returns true if the stack is empty.
*/
public boolean empty() {
return size() == 0;
}
/**
* Sees if an object is on the stack.
* @param o the desired object
* @return the distance from the top, or -1 if it is not found.
*/
public int search(Object o) {
int i = lastIndexOf(o);
if (i >= 0) {
return size() - i;
}
return -1;
}
}