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这是java.util包下的Stack类，你可以看一下它是如何实现的，至于用法，无非就是push，pop，peek等操作等
/*
* @636f707962616964757a686964616f31333234313966(#)Stack.java 1.30 05/11/17
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util;
/**
* The Stack class represents a last-in-first-out
* (LIFO) stack of objects. It extends classVectorwith five
* operations that allow a vector to be treated as a stack. The usual
*pushandpopoperations are provided, as well as a
* method topeekat the top item on the stack, a method to test
* for whether the stack isempty, and a method tosearch
* the stack for an item and discover how far it is from the top.
*
* When a stack is first created, it contains no items.
*
*
A more complete and consistent set of LIFO stack operations is
* provided by the {@link Deque} interface and its implementations, which
* should be used in preference to this class. For example:
*
{@code* Deque stack = new ArrayDeque();}
*
* @author Jonathan Payne
* @version 1.30, 11/17/05
* @since JDK1.0
*/
public
class Stack extends Vector {
/**
* Creates an empty Stack.
*/
public Stack() {
}
/**
* Pushes an item onto the top of this stack. This has exactly
* the same effect as:
*
* addElement(item)
*
* @param item the item to be pushed onto this stack.
* @return the item argument.
* @see java.util.Vector#addElement
*/
public E push(E item) {
addElement(item);
return item;
}
/**
* Removes the object at the top of this stack and returns that
* object as the value of this function.
*
* @return The object at the top of this stack (the last item
* of theVectorobject).
* @exception EmptyStackException if this stack is empty.
*/
public synchronized E pop() {
E obj;
int len = size();
obj = peek();
removeElementAt(len - 1);
return obj;
}
/**
* Looks at the object at the top of this stack without removing it
* from the stack.
*
* @return the object at the top of this stack (the last item
* of theVectorobject).
* @exception EmptyStackException if this stack is empty.
*/
public synchronized E peek() {
int len = size();
if (len == 0)
throw new EmptyStackException();
return elementAt(len - 1);
}
/**
* Tests if this stack is empty.
*
* @return true if and only if this stack contains
* no items; false otherwise.
*/
public boolean empty() {
return size() == 0;
}
/**
* Returns the 1-based position where an object is on this stack.
* If the objectooccurs as an item in this stack, this
* method returns the distance from the top of the stack of the
* occurrence nearest the top of the stack; the topmost item on the
* stack is considered to be at distance1. Theequals
* method is used to compareoto the
* items in this stack.
*
* @param o the desired object.
* @return the 1-based position from the top of the stack where
* the object is located; the return value -1
* indicates that the object is not on the stack.
*/
public synchronized int search(Object o) {
int i = lastIndexOf(o);
if (i >= 0) {
return size() - i;
}
return -1;
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = 1224463164541339165L;
}
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