Java 模拟栈结构

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转：http://blog.csdn.net/jjwwmlp456/article/details/40346039

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;      }            //size      public 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();      }            //size      public 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());      }  }

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