Java容器Stack

Stack继承关系

Collection  接口AbstractCollectionAbstractListVectorStack

方法

public E push 元素在栈顶，最后一个元素
public synchronized E pop() 删除并返回栈顶元素（最后一个）
public synchronized E peek()返回栈顶元素（最后一个）
public synchronized int search(Object o)返回元素所在位置（反向位置）
public boolean empty() 是否为空

常用方法测试

import java.util.Iterator;
import java.util.List;
import java.util.Stack;import lombok.extern.slf4j.Slf4j;@Slf4j
public class StackTest {public static void main(String[] args) {Stack stack=new Stack<>();for(int i=0;i<6;i++){stack.push(i);}// 遍历并打印出该栈iteratorStack(stack);// 查找"2"在栈中的位置，并输出log.info("value 2 in {}",stack.search(2));// pop栈顶元素之后，遍历栈log.info("pop {}",stack.pop());iteratorStack(stack);// peek栈顶元素之后，遍历栈log.info("peek {}",stack.peek());iteratorStack(stack);// 通过Iterator去遍历Stack}// 遍历public static void iteratorStack(List list) {Iterator it = list.iterator();while (it.hasNext()) {log.info("{}", it.next());}}
}

输出

2019-07-11 14:45:39,223   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 0
2019-07-11 14:45:39,229   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 1
2019-07-11 14:45:39,229   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 2
2019-07-11 14:45:39,229   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 3
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 4
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 5
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - value 2 in 4
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - pop 5
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 0
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 1
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 2
2019-07-11 14:45:39,230   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 3
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 4
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - peek 4
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 0
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 1
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 2
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 3
2019-07-11 14:45:39,231   [main] INFO  com.fang.java.javabase.firstcollection.StackTest  - 4

源码 openJdk 1.8

/** Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.** This code is free software; you can redistribute it and/or modify it* under the terms of the GNU General Public License version 2 only, as* published by the Free Software Foundation.  Oracle designates this* particular file as subject to the "Classpath" exception as provided* by Oracle in the LICENSE file that accompanied this code.** This code 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* version 2 for more details (a copy is included in the LICENSE file that* accompanied this code).** You should have received a copy of the GNU General Public License version* 2 along with this work; if not, write to the Free Software Foundation,* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.** Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA* or visit www.oracle.com if you need additional information or have any* questions.*/package java.util;/*** The <code>Stack</code> class represents a last-in-first-out* (LIFO) stack of objects. It extends class <tt>Vector</tt> with five* operations that allow a vector to be treated as a stack. The usual* <tt>push</tt> and <tt>pop</tt> operations are provided, as well as a* method to <tt>peek</tt> at the top item on the stack, a method to test* for whether the stack is <tt>empty</tt>, and a method to <tt>search</tt>* the stack for an item and discover how far it is from the top.* <p>* When a stack is first created, it contains no items.** <p>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:* <pre>   {@code*   Deque<Integer> stack = new ArrayDeque<Integer>();}</pre>** @author  Jonathan Payne* @since   JDK1.0*/
public
class Stack<E> extends Vector<E> {/*** Creates an empty Stack.*/public Stack() {}/*** Pushes an item onto the top of this stack. This has exactly* the same effect as:* <blockquote><pre>* addElement(item)</pre></blockquote>** @param   item   the item to be pushed onto this stack.* @return  the <code>item</code> 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 the <tt>Vector</tt> object).* @throws  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 the <tt>Vector</tt> object).* @throws  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  <code>true</code> if and only if this stack contains*          no items; <code>false</code> otherwise.*/public boolean empty() {return size() == 0;}/*** Returns the 1-based position where an object is on this stack.* If the object <tt>o</tt> occurs 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 distance <tt>1</tt>. The <tt>equals</tt>* method is used to compare <tt>o</tt> to 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 <code>-1</code>*          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;
}