Java 模拟栈结构

栈和队列：

一般是作为程序员的工具，用于辅助构思算法，生命周期较短，运行时才被创建

访问受限，在特定时刻，只有一个数据可被读取或删除

是一种抽象的结构，内部的实现机制，对用户不可见，比如用数组、链表来实现栈

栈：

同时，只允许一个数据被访问，后进先出

对于入栈和出栈的时间复杂度都为O(1),即不依赖栈内数据项的个数，操作比较快

例，使用数组作为栈的存储结构

public class StackS<T> {private int max;private T[] ary;private int top;//指针，指向栈顶元素的下标public StackS(int size) {this.max = size;ary = (T[]) new Object[max];top = -1;}// 入栈public void push(T data) {if (!isFull())ary[++top] = data;}// 出栈public T pop() {if (isEmpty()) {return null;}return ary[top--];}// 查看栈顶public T peek() {return ary[top];}//栈是否为空public boolean isEmpty() {return top == -1;}//栈是否满public boolean isFull() {return top == max - 1;}//sizepublic int size() {return top + 1;}public static void main(String[] args) {StackS<Integer> stack = new StackS<Integer>(3);for (int i = 0; i < 5; i++) {stack.push(i);System.out.println("size:" + stack.size());}for (int i = 0; i < 5; i++) {Integer peek = stack.peek();System.out.println("peek:" + peek);System.out.println("size:" + stack.size());}for (int i = 0; i < 5; i++) {Integer pop = stack.pop();System.out.println("pop:" + pop);System.out.println("size:" + stack.size());}System.out.println("----");for (int i = 5; i > 0; i--) {stack.push(i);System.out.println("size:" + stack.size());}for (int i = 5; i > 0; i--) {Integer peek = stack.peek();System.out.println("peek:" + peek);System.out.println("size:" + stack.size());}for (int i = 5; i > 0; i--) {Integer pop = stack.pop();System.out.println("pop:" + pop);System.out.println("size:" + stack.size());}}}

上面的例子，有一个maxSize的规定，因为数组是要规定大小的，若想无限制，可以使用其他结构来做存储，当然也可以new一个新的长度的数组。

例，使用LinkedList存储来实现栈

/** * 使用LinkedList存储来实现栈 * @author stone * * @param <T> */public class StackSS<T> {private LinkedList<T> datas;public StackSS() {datas = new LinkedList<T>();}// 入栈public void push(T data) {datas.addLast(data);}// 出栈public T pop() {return datas.removeLast();}// 查看栈顶public T peek() {return datas.getLast();}//栈是否为空public boolean isEmpty() {return datas.isEmpty();}//sizepublic int size() {return datas.size();}public static void main(String[] args) {StackS<Integer> stack = new StackS<Integer>(3);for (int i = 0; i < 5; i++) {stack.push(i);System.out.println("size:" + stack.size());}for (int i = 0; i < 5; i++) {Integer peek = stack.peek();System.out.println("peek:" + peek);System.out.println("size:" + stack.size());}for (int i = 0; i < 5; i++) {Integer pop = stack.pop();System.out.println("pop:" + pop);System.out.println("size:" + stack.size());}System.out.println("----");for (int i = 5; i > 0; i--) {stack.push(i);System.out.println("size:" + stack.size());}for (int i = 5; i > 0; i--) {Integer peek = stack.peek();System.out.println("peek:" + peek);System.out.println("size:" + stack.size());}for (int i = 5; i > 0; i--) {Integer pop = stack.pop();System.out.println("pop:" + pop);System.out.println("size:" + stack.size());}}}

例，单词逆序，使用Statck结构

public class WordReverse {public static void main(String[] args) {reverse("株式会社");}static void reverse(String word) {if (word == null) return;StackSS<Character> stack = new StackSS<Character>();char[] charArray = word.toCharArray();int len = charArray.length;for (int i = 0; i <len; i++ ) {stack.push(charArray[i]);}StringBuilder sb = new StringBuilder();while (!stack.isEmpty()) {sb.append(stack.pop());}System.out.println("反转后：" + sb.toString());}}

打印：

反转后：社会式株