數組實現棧

package com.yudaodata.protocol809.task;


import java.util.Arrays;
import java.util.EmptyStackException;

public class ArrayStack<T> {
 private Object[] elements = new Object[16]; //數組大小默認16
 private int count; //1.-1後指向棧內末尾的元素 2.統計棧內元素的數量

 public void push(T e) {
 //數組擴容
 if (count == elements.length) {
 elements = Arrays.copyOf(elements, 2 * count + 1);
 }
 elements[count++] = e;
 }

 public T pop() {
 if (count == 0) {
 throw new EmptyStackException();
 }
 T o = (T) elements[--count];
 elements[count] = null; //防止內存泄漏
 return o;
 }

 public static void main(String[] args) {
 ArrayStack<Integer> arrayStack = new ArrayStack<>();
 arrayStack.push(1);
 arrayStack.push(2);
 arrayStack.push(3);
 System.out.println(arrayStack.pop()); //2
 System.out.println(arrayStack.pop()); //1
 System.out.println(arrayStack.pop()); //1
 }}