Question

jsp文件

<html>
<body>
<form method="post" action="index.jsp" />

<% 
String integer = request.getParameter("integer"); 
%>

<%
int x = 0;
try { x = Integer.parseInt("integer"); }
catch (Exception e) { x = 0; }
%>

<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />

</form>
</body>
</html>

每次点击提交按钮时，如何添加或增加x输出？

Answer 1

Integer.parseInt("integer"); -> "integer" string is not a number therefore it will be a wrong format.

并且每次初始化x = 0并且x

没有增量你可以试试这个：

<form method="post" action="" />

<%
  String integer = request.getParameter("integer");          
  int x = integer != null ? Integer.parseInt(integer) : 0;      
  ++x;
%>

<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />

Answer 2

<html>
<body>
<form method="post" action="index.jsp" />

<% 
String integer = request.getParameter("integer"); 
%>

<%
int x = 0;
try { x = Integer.parseInt("integer"); }
catch (Exception e) { x = 0; }
x = x + 1;
%>

<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />

</form>
</body>
</html>

每次点击提交按钮时，如何添加一个或递增整数？

2 个答案: