EL and regular expression
in [Java Programming]
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From: francan on 28 Feb 2010 09:32 I am trying to use a Regular Expression in Tomcat 6.0.20 with EL and its not working: <c:set var="info" value="joe2222" /> Here are results = ${fn:replace(info,'\d+','')}<br><br> Error message - org.apache.jasper.JasperException: An exception occurred processing JSP page /jsp/reg2.jsp at line 14 11: 12: 13: <c:set var="info" value="joe2222" /> 14: Here are results = ${fn:replace(info,'\d+','')}<br><br> Please advise.
From: Lew on 28 Feb 2010 09:48 francan wrote: > I am trying to use a Regular Expression in Tomcat 6.0.20 with EL and > its not working: > <c:set var="info" value="joe2222" /> > Here are results = ${fn:replace(info,'\d+','')}<br><br> > > > Error message - > org.apache.jasper.JasperException: An exception occurred processing > JSP page /jsp/reg2.jsp at line 14 > > 11: > 12: > 13: <c:set var="info" value="joe2222" /> > 14: Here are results = ${fn:replace(info,'\d+','')}<br><br> > > > Please advise. Find the exception that occurred. It will give you details. From the message it looks like a compiler error, but stopping at "an exception" gives too little detail. I suspect you have insufficient backslashes, and that the Java compiler is trying to parse '\d', which raises a compiler error. -- Lew
From: francan on 28 Feb 2010 10:49 On Feb 28, 9:48 am, Lew <no...(a)lewscanon.com> wrote: > francan wrote: > > I am trying to use a Regular Expression in Tomcat 6.0.20 with EL and > > its not working: > > <c:set var="info" value="joe2222" /> > > Here are results = ${fn:replace(info,'\d+','')}<br><br> > > > Error message - > > org.apache.jasper.JasperException: An exception occurred processing > > JSP page /jsp/reg2.jsp at line 14 > > > 11: > > 12: > > 13: <c:set var="info" value="joe2222" /> > > 14: Here are results = ${fn:replace(info,'\d+','')}<br><br> > > > Please advise. > > Find the exception that occurred. It will give you details. From the message > it looks like a compiler error, but stopping at "an exception" gives too > little detail. > > I suspect you have insufficient backslashes, and that the Java compiler is > trying to parse '\d', which raises a compiler error. > > -- > Lew- Hide quoted text - > > - Show quoted text - Thanks, I tried the below and it worked and got no error but it didnt substitute the value joe2222 for joe where the \d should replace the number: <c:set var="info" value="joe2222" /> Here are results = ${fn:replace(info,'\\d+','')} Please advise.
From: Lew on 28 Feb 2010 11:23 francan wrote: > I tried the below and it worked and got no error but it didnt > substitute the value joe2222 for joe where the \d should replace the > number: Don't you mean it didn't substitute the value "joe" for "joe2222"? (You substitute the new for the old; you replace the old with the new.) > <c:set var="info" value="joe2222" /> > Here are results = ${fn:replace(info,'\\d+','')} Are you sure you have the right number of backslashes? It seems like you haven't researched how many layers translate strings, replacing doubled backslashes with single ones. Programming requires looking up documentation for the tools you use, in addition to just trying stuff to see what happens. The expression-language parser probably does that, the 'fn:replace' tag probably does that and the Java parser certainly does that. I don't know the number myself off the top of my head (I'd have to look up the docs), but I suspect that there are three doublings going on. Even when you do just try stuff, you should track what you changed and what was the exact behavior you got, against the exact behavior you wanted. Speaking of which, your question provides very little data on which to base an answer. You hint at the behavior you want and you completely omit the behavior you got. You should follow the guidelines set forth in <http://sscce.org/> -- Lew
From: Daniel Pitts on 28 Feb 2010 18:36 On 2/28/2010 8:23 AM, Lew wrote: > francan wrote: >> I tried the below and it worked and got no error but it didnt >> substitute the value joe2222 for joe where the \d should replace the >> number: > > Don't you mean it didn't substitute the value "joe" for "joe2222"? (You > substitute the new for the old; you replace the old with the new.) > >> <c:set var="info" value="joe2222" /> >> Here are results = ${fn:replace(info,'\\d+','')} > > Are you sure you have the right number of backslashes? > > It seems like you haven't researched how many layers translate strings, > replacing doubled backslashes with single ones. Programming requires > looking up documentation for the tools you use, in addition to just > trying stuff to see what happens. The expression-language parser > probably does that, the 'fn:replace' tag probably does that and the Java > parser certainly does that. I don't know the number myself off the top > of my head (I'd have to look up the docs), but I suspect that there are > three doublings going on. Actually, I'm fairly certain that the string in JSP is the same as in Java, so "\\d+" would be correct. Now, the I wonder if fn:replace actually takes a regex. I don't think it does. > > Even when you do just try stuff, you should track what you changed and > what was the exact behavior you got, against the exact behavior you wanted. > > Speaking of which, your question provides very little data on which to > base an answer. You hint at the behavior you want and you completely > omit the behavior you got. > > You should follow the guidelines set forth in > <http://sscce.org/> > -- Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>
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