Java数据结构与算法之stack栈

目录：
1.栈概述
2.数组实现自定义栈
3.链表实现自定义栈
4.集合实现自定义栈

1.栈概述
栈和队列一样，也是线性表的一种，它唯一的特点是需要满足先进后出(FILO)的规则，也就是只能对栈的一头进行操作，添加数据
称为压栈，移除数据称为弹栈。而在java中栈的实现可以通过数组，链表，集合(ArrayList/LinkedList)3种方式进行实现。


2.数组实现自定义栈
(1)自定义栈接口CustomStack.java

package com.datastructure.test;public interface CustomStack<T> {//压栈方法public void push(T data)throws Exception;//弹栈/移除顶部元素，并返回对应的数据public T pop()throws Exception;//获取stact第一个元素public T peek();//判断栈是否为空public boolean empty();//返回栈中元素的个数public int size();}

(2)数组自定义栈类CustomArrayStack.java

package com.datastructure.test;public class CustomArrayStack<T> implements CustomStack<T> {static final int defaultSize = 15;//指示顶部元素的位置private int size;private T[] arrays;/* * 无参构造方法，做一些初始化的操作 */@SuppressWarnings("unchecked")public CustomArrayStack() {size = 0;arrays = (T[]) new Object[defaultSize];}/* * 根据用户自定义数组大小初始化数组 */@SuppressWarnings("unchecked")public CustomArrayStack(int customSize) {size = 0;arrays = (T[]) new Object[customSize];}/* * 向栈顶添加元素 */@Overridepublic void push(T data) throws Exception {if (size<arrays.length) {arrays[size] = data;size++;}else {throw new Exception("数组栈已经满啦!");}}/* * 将栈顶的元素移除 */@Overridepublic T pop() throws Exception {T topData;if (empty()) {throw new Exception("数组栈为空!");}else {topData = arrays[size-1];size--;}return topData;}/* * 获取栈顶的元素 */@Overridepublic T peek() {return arrays[size-1];}/* * 判断栈是否为空 */@Overridepublic boolean empty() {return size==0;}/* * 返回栈的长度 */@Overridepublic int size() {return size;}}

(3)测试类CustomArrayStackTest.java

package com.datastructure.test;public class CustomArrayStackTest {public static void main(String[] args) {CustomArrayStack<String> stack = new CustomArrayStack<>(10);System.out.println("是否为空:"+stack.empty());try {stack.push("I");stack.push("am");stack.push("andy");} catch (Exception e) {e.printStackTrace();}System.out.println("栈顶元素:"+stack.size());System.out.println("栈顶元素:"+stack.peek());try {System.out.println("移除元素:"+stack.pop());} catch (Exception e) {e.printStackTrace();}System.out.println("栈顶元素:"+stack.size());System.out.println("栈顶元素:"+stack.peek());}}

(4)测试控制台输出

是否为空:true栈长度:3栈顶元素:andy移除元素:andy栈长度:2栈顶元素:am

3.链表实现自定义栈
(1)自定义栈接口CustomStack.java（与2一致）
(2)链表自定义栈类CustomLinkedStack.java

package com.datastructure.test;public class CustomLinkedStack<T> implements CustomStack<T> {private int size;private Node topNode;@Overridepublic void push(T data) throws Exception {Node newTopNode;if (empty()) {    newTopNode = new Node(data, null);}else {    newTopNode = new Node(data, topNode);}topNode = newTopNode;size++;}@Overridepublic T pop() throws Exception {Node oldTopNode = topNode;topNode = topNode.nextNode;size--;return oldTopNode.data;}@Overridepublic T peek() {return topNode.data;}@Overridepublic boolean empty() {return size==0;}@Overridepublic int size() {return size;}/** * 节点内部类 */class Node{private T data;private Node nextNode;public Node(T data,Node nextNode){this.data = data;this.nextNode = nextNode;}}}

(3)测试类CustomLinkedStackTest.java

package com.datastructure.test;public class CustomLinkedStackTest {public static void main(String[] args) {CustomLinkedStack<String> stack = new CustomLinkedStack<>();System.out.println("是否为空:"+stack.empty());try {stack.push("I");stack.push("am");stack.push("andy");} catch (Exception e) {e.printStackTrace();}System.out.println("栈长度:"+stack.size());System.out.println("栈顶元素:"+stack.peek());try {System.out.println("移除元素:"+stack.pop());} catch (Exception e) {e.printStackTrace();}System.out.println("栈长度:"+stack.size());System.out.println("栈顶元素:"+stack.peek());}}

(4)测试结果与2一致

4.集合实现自定义栈
(1)自定义栈接口CustomStack.java（与2一致）
(2)集合类LinkedList实现栈自定义CustomCollectionStack.java

package com.datastructure.test;import java.util.LinkedList;class CustomCollectionStack<T> implements CustomStack<T> {private LinkedList<T> linkedList = new LinkedList<>();public CustomCollectionStack() {}@Overridepublic void push(T data) throws Exception {linkedList.add(data);}@Overridepublic T pop() throws Exception {return linkedList.removeLast();}@Overridepublic T peek() {return linkedList.getLast();}@Overridepublic boolean empty() {return linkedList.isEmpty();}@Overridepublic int size() {return linkedList.size();}}

(3)测试类CustomCollectionStackTest.java

package com.datastructure.test;public class CustomCollectionStackTest {public static void main(String[] args) {CustomCollectionStack<String> stack = new CustomCollectionStack<>();System.out.println("是否为空:"+stack.empty());try {stack.push("I");stack.push("am");stack.push("andy");} catch (Exception e) {e.printStackTrace();}System.out.println("栈长度:"+stack.size());System.out.println("栈顶元素:"+stack.peek());try {System.out.println("移除元素:"+stack.pop());} catch (Exception e) {e.printStackTrace();}System.out.println("栈长度:"+stack.size());System.out.println("栈顶元素:"+stack.peek());}}

(4)结果与2一致

文章：

Java数据结构与算法之学习路线

Java数据结构与算法之Array数组

Java数据结构与算法之LinkedList单链表

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Java数据结构与算法之stack栈