package algorithm;
import java.util.Arrays;

import java.util.Iterator;/**
• @author Administrator
• @date 2022-09-12 16:38
• 数组栈
*/
public class MyArrayStack {
// 定义一个数组
private Object[] elementData;
// 顶部的索引
private int topIndex;
// 构造方法确定栈的长度
public MyArrayStack(int size) {
this.elementData = new Object[size];
}
/**• 定义迭代器
• @return
*/
@Override
public Iterator iterator() {
return new MyArrayStackIter();
}
class MyArrayStackIter implements Iterator{
@Override
public boolean hasNext() {
return topIndex != elementData.length;
}
@Override
public E next() {
return pop();
}
@Override
public void remove() {
pop();
}
}
public boolean push(E element){
// 判断扩容两倍
if(topIndex >= elementData.length){
elementData = Arrays.copyOf(elementData,elementData.length << 1);
}
elementData[topIndex++] = element;
return true;
}
// 删除并出栈 是否删除就看topIndex本身的大小是否改变
public E pop(){
if(topIndex <= 0){
throw new RuntimeException("栈为空");
}
return (E) elementData[--topIndex];
}
// 不删除出栈 栈顶元素
public E peek(){
if(topIndex <= 0){
throw new RuntimeException("栈为空");
}
return (E) elementData[topIndex - 1];
}
public static void main(String[] args) {
MyArrayStack myArrayStack = new MyArrayStack(5);
myArrayStack.push("11");
myArrayStack.push("22");
myArrayStack.push("33");
System.out.println("-----------");
System.out.println(myArrayStack.pop());
System.out.println(myArrayStack.pop());
System.out.println(myArrayStack.pop());
System.out.println(myArrayStack.pop());
//    Iterator iterator = myArrayStack.iterator();
//    while (iterator.hasNext()){
//      System.out.println(iterator.next());
//    }
}
}