package com.lzq;

public interface Stack {
public void push(Object obj) throws Exception;
public Object pop()throws Exception;
public Object getTop()throws Exception;
public boolean notEmpty();
}
class SeqStack implements Stack{
	final int defaultSize=10;
	int top;
	Object[] stack;
	int maxStackSize;
	public SeqStack(){
		initiate(defaultSize);
	}
	public SeqStack(int sz){
		initiate(sz);
	}
	 void initiate(int sz) {
		// TODO 自动生成方法存根
		maxStackSize=sz;
		top=0;
		stack=new Object[sz];
	}

	public Object getTop() throws Exception {
		// TODO 自动生成方法存根
		if(top==0){
			throw new Exception("堆栈以空");
		}
		return stack[top-1];
	}

	public boolean notEmpty() {
		// TODO 自动生成方法存根
		return(top>0);
	}

	public Object pop() throws Exception {
		// TODO 自动生成方法存根
		if(top==0){
			throw new Exception("退栈以空");
		}
		top--;
		return stack[top];
	}

	public void push(Object obj) throws Exception {
		// TODO 自动生成方法存根
		if(top==maxStackSize){
			throw new Exception("退栈已满！");
		}
		stack[top]=obj;
		top++;
	}
	
}

package com.lzq;

public class Test2 {
public static void main(String[] args) {
	
	SeqStack myStack=new SeqStack();
	String s="abcd123";
	char[] c=s.toCharArray();
	int n=7;
	try{
		for(int i=0;i<n;i++){
			myStack.push(new Character(c[i]));
		}
		System.out.println("当前栈顶元素为："+myStack.getTop());
		System.out.println("元素出栈序列为：");
		while(myStack.notEmpty()){
			System.out.println(myStack.pop());
		}
	}catch(Exception e){
		System.out.println(e.getMessage());
	}

}
}