stacklist.java

使用JAVA语言实现的四则运算(加,减,乘,除运算)

public class StackList
{
	
	private ListNode topOfStack;
	
	
	public StackList()
	{
		topOfStack = null;
	}
	
	public void makeEmpty()
	{
		topOfStack = null;
	}
	
	public boolean isEmpty()
	{
		return topOfStack == null;
	}
	
	public void push(String x)
	{
		topOfStack = new ListNode(x,topOfStack);
	}
	
	public String top()
	{
		if(isEmpty())
		return "#";
		else
		return topOfStack.element;
	}
	public void pop() 
	{
		if(!isEmpty())
	     
		topOfStack=topOfStack.next;
	}
	public String topAndPop()
	{
		if(isEmpty())
		return  "#";
		
	    String topItem   = topOfStack.element;
		topOfStack    = topOfStack.next;
		return topItem;
	}
}