How to avoid checking for null in jsp

Question

I want to use JSP page to return dynamic xml.The problem I'm facing is that I've model where some values are null and when they are null I don't wont to display them. So I can do following:

if(ampApInfo.getColourcd().equals(null)){   %>

    <ColourCd><%=  ampApInfo.getColourcd() %></ColourCd>

  <%} else if(ampApInfo.getSzWeightColourcd().equals(null)){ %> 


    <SzWeightColourcd><%= ampApInfo.getSzWeightColourcd()  %></SzWeightColourcd>

  <%}%> //and so forth

But this makes my code ugly and not practical. Is there a way to avoid that?? Can you please provide me with an example how to do it or point to one. Thanks a lot.

Answer 1

The ugliness is caused by using old fashioned scriptlets instead of JSTL/EL. With JSTL, it would look more self-documenting (as it uses XML-like markup). With EL you can use the ${} notation to access bean properties.

Something like this:

<c:choose>
    <c:when test="${not empty ampApInfo.colourcd}">
        <ColourCd>${ampApInfo.colourcd}</ColourCd>
    </c:when>
    <c:when test="${not empty ampApInfo.szWeightColourcd}">
        <ColourCd>${ampApInfo.szWeightColourcd}</ColourCd>
    </c:when>
    <c:otherwise />
</c:choose>

(note that I inversed the condition, you were printing the elements when the value is null, which contradicts your own functional requirement)

See also:

• How to avoid Java code in JSP files?

Answer 2

if(object1!=null){

do something

}else{

do something else

}

possible duplicate Avoiding != null statements

Answer 3

Try ternary operator. Also, I think, you have missed not of in your code, so if your code is,

     if(ampApInfo.getColourcd() != null){   %>

    <ColourCd><%=  ampApInfo.getColourcd() %></ColourCd>

  <%} else if(ampApInfo.getSzWeightColourcd() != null){ %> 

    <SzWeightColourcd><%= ampApInfo.getSzWeightColourcd()  %></SzWeightColourcd>

  <%}%> //and so forth

then, you shall transform to like this.

<%
    String str1 = "tag1 data";
    String str2 = "tag2 data";
    String finalStr = str1 != null ? "<tag1>" + str1 + "</tag1>" : (str2 != null ? "<tag2>" + str2 + "</tag2>" : "");
%>
  <%= finalStr%>