package com.sjtu.design.excise;

//棧類

/**

 * 

 * @author tsh11089

 *

 */

public class SqStack {

private Object[] stackElem;

private int top;

// 初始化棧

public SqStack(int maxStack) {

stackElem = new Object[maxStack];

top = 0;

}

// 入棧

public void push(Object stack) {

if (top == stackElem.length) {

// throw new Exception("棧已滿!");

System.out.println("棧已滿!");

} else {

stackElem[top++] = stack;

}

}

// 出棧

public Object pop() {

if (top == 0) {

// throw new Exception("棧為空!");

System.out.println("棧為空!");

return null;

} else {

return stackElem[--top];// 刪除然后返回現(xiàn)在的棧頂

}

}

// 打印(從棧頂?shù)綏５?

public void display() {

for (int i = length() - 1; i >= 0; i--) {

System.out.print(stackElem[i] + " ");

}

System.out.println();

}

// 元素個(gè)數(shù)

public int length() {

return top;

}

// 棧頂

public Object peek() {

if (!isEmpty())

return stackElem[top - 1];

else

return null;

}

// 清空

public void clear() {

top = 0;

}

// 釋放棧內(nèi)存空間

public void free(SqStack stack) {

if (stack != null) {

stack = null;

}

}

// ?？?/p>

public boolean isEmpty() {

return top == 0;

}

// 棧滿

public boolean isFull() {

return top == stackElem.length;

}

public static void main(String[] args) {

SqStack sqStack1 = new SqStack(3);

sqStack1.push(1);

sqStack1.push(4);

sqStack1.push(7);

System.out.print("打印輸出：  ");

sqStack1.display();

int top1 = (Integer) sqStack1.peek();

System.out.println("棧頂:  " + top1);

sqStack1.pop();

System.out.print("彈出棧頂，打印輸出:  ");

sqStack1.display();

System.out.println("---------------------------------------");

SqStack sqStack2 = new SqStack(2);

sqStack2.push(2);

sqStack2.push(5);

sqStack2.push(8);

System.out.print("打印輸出：  ");

sqStack2.display();

int top2 = (Integer) sqStack2.peek();

System.out.println("棧頂:  " + top2);

sqStack2.pop();

System.out.print("彈出棧頂，打印輸出:  ");

sqStack2.display();

System.out.println("---------------------------------------");

SqStack sqStack3 = new SqStack(0);

sqStack3.push(3);

sqStack3.push(6);

sqStack3.push(9);

System.out.print("打印輸出：  ");

sqStack3.display();

int top3 = (Integer) sqStack3.peek();

System.out.println("棧頂:  " + top3);

sqStack3.pop();

System.out.print("彈出棧頂，打印輸出:  ");

sqStack3.display();

}

}