How to check condition with JSP variable?

Question

Hello i am New jsp i want to check condition in jsp. whether value is null or not.? i have write following code in jsp page

   <% String s = request.getParameter("search"); %>
    <%=s %>
    <% if (<%=s ==null) { %> 
     <div>textbox is empty</div>

   <% } else { %>
   <div>textbox value..
    <% } %>

i get textbox value in variable if textbox value is null then it should display first message othervise second. tell me how to do?

By the way, the best practice is to avoid using scriptlet in your jsp. http://stackoverflow.com/questions/3177733/how-to-avoid-java-code-in-jsp-files — Drogba, Apr 24 '13 at 07:36
This is more of a syntax problem - I think once Rajan gets his answer, the question ought to be deleted. — aquaraga, Apr 24 '13 at 07:37
your question say if textbox value is null then execute `if` otherwise `else`? what is your textbox value? value of s ? — harsh, Apr 24 '13 at 07:40

score 9 · Answer 1 · edited May 23 '17 at 12:24

9

The best way to do it is with JSTL. Please avoid scriptlets in JSP.

<c:choose>
  <c:when test="${empty search}">
   <div>textbox is empty</div>
  </c:when>
  <c:otherwise>
    <div>textbox value is ${search}</div>
  </c:otherwise>
</c:choose>

edited May 23 '17 at 12:24

Community

1
1

answered Apr 24 '13 at 07:40

AllTooSir

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harsh · Accepted Answer · 2013-04-24T07:42:54.507

5

    <% String s = request.getParameter("search"); %>
    <%=s %>
    <% if (s==null || s.isEmpty()) { %> 
     <div>textbox is empty</div>

   <% } else { %>
   <div>textbox value..
    <% } %>

edited Apr 24 '13 at 07:42

answered Apr 24 '13 at 07:31

harsh

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if i dont insert value in text box then also it also go to else part – Kapil Apr 24 '13 at 07:37
1

@Rajan can you check what value of `s` is printed? it might not be `null` but empty `""` or having spaces. check modified answere.. – harsh Apr 24 '13 at 07:42

NilsH · Answer 3 · 2013-04-24T07:36:50.537

3

Does it even compile? <% if (<%=s ==null) { %> should at least be

<% if (s == null) { %>

If you want to check for empty string as well, do

<% if(s == null || s.trim().length == 0) { %>

edited Apr 24 '13 at 07:36

answered Apr 24 '13 at 07:30

NilsH

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<% if (s==null) { %>
Condition is true!
<% } else { %>
Condition is false
<% } %> – Kapil Apr 24 '13 at 07:33
it always goes to else part – Kapil Apr 24 '13 at 07:34
Then the String is not null. – NilsH Apr 24 '13 at 07:35
my string is null... i dont enter any value to text box – Kapil Apr 24 '13 at 07:38
Your if test says otherwise. Even though it doesn't have a visible value doesn't mean it have to be null. – NilsH Apr 24 '13 at 07:39
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/28785/discussion-between-rajan-and-nilsh) – Kapil Apr 24 '13 at 07:40

ntstha · Answer 4 · 2013-04-24T07:47:50.090

<% String s = request.getParameter("search"); 
     if (s ==null) { %> 
     <div>textbox is empty</div>

   <% } else { %>
   <div><span><%=s%></span></div>
    <% } %>

edited to include empty string

<% 
       String s="";
     if(request.getParameter("search")!=null)
      {
          s=request.getParamater("search");
      }
     if(s.trim().length()==0)
        {%>
           <div>Empty Field</div>
        <%}
          else{%>
              <div><span><%=s%></div>
           <%}%>

score 1 · Answer 5 · answered Apr 24 '13 at 07:35

1

<% String s = request.getParameter("search"); %>
    <%=s %>
    <% if (s ==null) { %> 
     <div>textbox is empty</div>

   <% } else { %>
   <div>textbox value..
    <% } %>

answered Apr 24 '13 at 07:35

Alpesh Gediya

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hello alpesh Gediya ... it also go to else part – Kapil Apr 24 '13 at 07:40

score 0 · Answer 6 · edited Apr 03 '18 at 04:02

0

In jsp, it is easy to check whether a variable is empty or not.

String search;
if(search.isEmpty()){
out.println("The variable is empty ?");
}
else{
out.println("The variable is Not empty ?");  
}

edited Apr 03 '18 at 04:02

Vishal Yadav

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answered Apr 02 '18 at 08:30

Bhagawat

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How to check condition with JSP variable?

6 Answers6