Friday, June 19, 2009

JSTL formatNumber as percentage gets invalid attribute error

fmt:formatNumber <formatNumber> invalid type attribute: "percentage" percent

The JSTL Tag Library documentation seems to indicate that to format a number as a percentage you'd use:

<fmt:formatNumber type="percentage" value="0.5"/>

This gives the error message
<formatNumber>, invalid type attribute: "percentage"

Although the documentation for type says "Specifies whether the value is to be formatted as number, currency, or percentage" these aren't the possible values - it's "percent" for percentage:

<fmt:formatNumber type="percent" value="0.5"/>

If you know a good reference for JSTL I'd like to know ...

The Appendix A from JSTL in Action is not bad - it documents possible values for formatNumber type at least.

Tuesday, June 16, 2009

Eclipse build errors - java.lang.object cannot be resolved

eclipse 3.4.0 ganymede The type java.lang.object "cannot be resolved" "Cannot find the class file" "refers to the missing type"

Opened eclipse, it needed to do a full workspace build (probably because ant scripts have updated class files and it needs to refresh). Random classes in the project now no longer compile. Examples of the errors being reported:

The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class filesMyClass.javaMyProject/src/com/exampleline 1Java Problem
The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this projectMyProjectUnknownJava Problem
The method myMethod(SomeClass) from the type MyOtherClass refers to the missing type (insert java type here: InputStream|File|Vector|IOException|etc)MyOtherClass.javaMyProject/src/com/exampleline 123Java Problem

It sounds like this has been a known issue (Bug 67414)that was resolved in 3.0 ... someone has commented that it's occurring for them in 3.4 as well.

In the mean time, the work around is to remove the JRE System Library from the project and then add it back again.
Here are the steps:
  1. Go to properties of project with the build error (right click > Properties)
  2. View the "Libraries" tab in the "Build Path" section
  3. Find the "JRE System Library" in the list (if this is missing then this error message is not an eclipse bug but a mis-configured project)
  4. Remove the "JRE System Library"
  5. Hit "Add Library ...", Select "JRE System Library" and add the appropriate JRE for the project (eg. 'Workspace default JRE')
  6. Hit "Finish" in the library selection and "OK" in the project properties and then wait for the re-build of the project
  7. Hopefully the error will be resolved ...