EL any function to get absolute value of a number?

Question

I know the ugly way

a>0 ? a : -a

but this is very annoyng when a is a relatively long expression.

OBJ1[\"x\"]-someVar>         


        

Answer 1

For plain jsp, you can create a custom EL function which delegates to Math#abs(int).

If you first just create a /WEB-INF/functions.tld file which look like follows:

    1.0
    Custom_Functions
    http://example.com/functions

    
        abs
        java.lang.Math
        int abs(int)
    

Then you'll be able to use it as follows:

<%@taglib uri="http://example.com/functions" prefix="f" %>
...
${f:abs(OBJ1["x"]-someVar)}

This solution also works for JSF, but if you are using JSF, OmniFaces has simplified this for you by providing its importFunctions (if not already using OmniFaces with JSF, you should start using it)

...
#{m:abs(-10)}

See also:

• Our EL wiki page