<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<html>
<head>
</head>
<body>
<form action="" method="post">
请输入姓名<input type="text" name="names"><br>
请输入密码<input type="text" name="password"><br>
<input type="submit" name="submit" value="验证">
<%
String names=request.getParameter("names");
String password=request.getParameter("password");
if(password.equals("good")){
%>
<jsp:forward page="jspforward.jsp">
<jsp:param value="<%=names %>" name="g"/>
<jsp:param value="you are success" name="mess"/>
</jsp:forward>
<%
}else{
%>
<jsp:forward page="jspforward.jsp">
<jsp:param value="<%=names %>" name="g"/>
<jsp:param value="you password is mistake " name="mess"/>
</jsp:forward>
<%
}
%>
</form>
</body>
</html>说我这一行出错 if(password.equals("good")){
编译没错误但到浏览器里有错了
pageEncoding="UTF-8"%>
<html>
<head>
</head>
<body>
<form action="" method="post">
请输入姓名<input type="text" name="names"><br>
请输入密码<input type="text" name="password"><br>
<input type="submit" name="submit" value="验证">
<%
String names=request.getParameter("names");
String password=request.getParameter("password");
if(password.equals("good")){
%>
<jsp:forward page="jspforward.jsp">
<jsp:param value="<%=names %>" name="g"/>
<jsp:param value="you are success" name="mess"/>
</jsp:forward>
<%
}else{
%>
<jsp:forward page="jspforward.jsp">
<jsp:param value="<%=names %>" name="g"/>
<jsp:param value="you password is mistake " name="mess"/>
</jsp:forward>
<%
}
%>
</form>
</body>
</html>说我这一行出错 if(password.equals("good")){
编译没错误但到浏览器里有错了
第一次进入页面的时候password是null,so
第一次进入页面的时候password是null,so
null调用equals方法当然报错了
if("good".equals(password))这么写就可以免去password为空的判断了。
一般为了避免 password = null 所以都用楼上那种判断