顺序堆栈的实现

public class SeqStack{
	final int defaultSize = 10;
	int top;
	Object[] stack;
	int maxStackSize;
	
	public SeqStack(){
		initiate(defaultSize);
	}
	
	public SeqStack(int sz){
		initiate(sz);
	}
	
	private void initiate(int sz){
		maxStackSize = sz;
		top = 0;
		stack = new Object[sz];
	}
	
	public void push(Object obj) throws Exception{   //把数据元素obj插入堆栈
		if(top == maxStackSize){
			throw new Exception("堆栈已满！");
		}
		stack[top] = obj;
		top ++;
	}
	
	public Object pop() throws Exception{          //出栈，删除的数据元素由函数返回
		if(top == 0){
			throw new Exception("堆栈已空！");
		}
		top --;
		return stack[top];
	}
	
	public Object getTop() throws Exception{      //取堆栈当前栈顶的数据元素并由函数返回
		if(top == 0){
			throw new Exception("堆栈已空！");
		}
		return stack[top - 1];
	}
	
	public boolean notEmpty(){      //若当前非空则函数返回true,不然函数返回false
		return (top > 0);
	}
}