EL表达式中的empty运算符和三元运算符_el表达式和三元运算符相反-优快云博客

本文链接：https://blog.youkuaiyun.com/wangyanming123/article/details/52425635

ELDemo1.java文件：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>EL运算</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
    <br/>------empty运算符--------<br/>
    <%
    pageContext.setAttribute("s1", "");
    pageContext.setAttribute("s2", null);
    List list = new ArrayList();
    list.add("aa");
    pageContext.setAttribute("list", list);
    String strs[] = {};
    pageContext.setAttribute("strs", strs);
     %>
    ${empty s1}<br/>
    ${empty s2}<br/>
    ${empty list}<br/>
    ${empty strs}<br/>
    <br/>------三元运算符--------<br/>
    <%
    pageContext.setAttribute("gender", "female");
     %>
     <input type="radio" name="gender" value="male" ${gender=='male'?'checked="checked"':''}/>男
     <input type="radio" name="gender" value="female" ${gender=='female'?'checked="checked"':''}/>女
  </body>
</html>