Why eclipse jsp editor cannot parse java block comment in sperate scriptlets?

Question

The Eclipse JSP editor cannot parse the Java block comment in seperate scriptlets like

<% /* %><span> blabla </span><% */ %>

Here's what it looks like in Eclipse:

In practice, we know the code between /* */ will be commented out, but eclipse editor shows code between as normal text. That is totally confusing.

I know this case should be avoided, but I got a huge amount of such code to read.

So is there any method to enable syntax highlighting for this case?

Test case:

<TABLE>
        <TR><TD>Normal text</TD></TR>
<% /* %><TR><TD>Unparsed comment</TD></TR><% */ %>
<% /*   <TR><TD>Parsed comment</TD></TR>     */ %>
<%--    <TR><TD>Parsed comment</TD></TR>      --%>
</TABLE>

Answer 1

That's a great way to write unmaintainable code. While you have a point that it might be technically a bug in the workings of the editor, I'd not rely on it to reliably work: A JSP is compiled into a servlet (turned inside out), then compiled to bytecode.

• I consider hiding code this way - instead of using <%-- --%> - to be intentionally evil and this style wouldn't pass (my) code review.
• Nothing prevents the JSP->Servlet compiler from generating block comments as well. Then you'd easily have nested block comments - illegal code - which would be invisible in the JSP (wouldn't happen with your example, but as soon as jsp tags are in the game, it might well be)

Take this behaviour as a hint that you should consider rewriting your code in a different way and don't rely on the JSP->Servlet compiler to always follow your current mental model. It might as well break with a future compiler-update in a year - and then you'd have to remember what you did here, why you did it. And you wouldn't have a clue why it worked all the time and suddenly stopped. You'll probably not attribute it to an update to the servlet container that someone did behind your back.