Use static methods in EL

Question

I'm facing a strange problem here with EL.

I just wanted to use String.join() in EL but it is not working.

#{String.join(',', myList)}

This is not doing anything in JSF except prevent my page to load. I know i can do this with <ui:repeat> but i need to use it in EL expression.

Any ideas ?

Fortunate

Answer 1

You can't call a static method with EL. Create a Bean with a method to call String.join()

@RequestScoped
@Named
public class StringBean {

    public String join(CharSequence delimiter, Iterable<? extends CharSequence> elements) {
        return String.join(delimiter, elements);
    }
}

So you can call #{stringBean.join(',', myList)}

Hartnett

I was trying to find a way to prevent this case... Thanks mate ! – Fortunate

There's another way though. You'll find out now you have the right terms/keywords. – Informant

You mean EL 3.0 for call static methods? – Hartnett

@Informant I wrote your answers about declaring EL with tag but i feel dumb i don't understand how can i'm supposed to do in my case (using String join) .... – Fortunate

Answer 2

i found an approach to this.

register your util class as a bean in the faces-config.xml

<managed-bean>
    <managed-bean-name>String</managed-bean-name>
    <managed-bean-class>java.lang.String</managed-bean-class>
    <managed-bean-scope>application</managed-bean-scope>
</managed-bean>

I am using org.apache.commons.lang3.ArrayUtils and it is working for me.

Hippel

Answer 3

You can write a custom function that exposes your static method as a function in EL. A similar question has been answered here.

Perorate