Why does <h:inputText required=“true”> allow blank spaces?

When I set required="true" in a <h:inputText>, it still allows blank spaces. I have been trying to modify the jsf-api.jar but I could not understand how to generate new a JAR, so I tried to modify the isEmpty() method from UIInput class and compile it, open the jsf-api.jar and replace it with the new one, but it did not work.

What I need is to do trim() when the user writes in a <h:inputText> to do not allow blank spaces. How can I achieve this?

If you want to download the jsf-api.jar resource, you can do it, just read how to at: http://javaserverfaces.java.net/checkout.html.


That's normal and natural behaviour and not JSF specific. A blank space may be perfectly valid input. The required="true" only kicks in on empty inputs, not in filled inputs. In JSF you can however just create a Converter for String class to automatically trim the whitespace.

public class StringTrimmer implements Converter {

    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        return value != null ? value.trim() : null;

    public String getAsString(FacesContext context, UIComponent component, Object value) {
        return (String) value;


Put this class somewhere in your project. It'll be registered automatically thanks to @FacesConverter and invoked automatically for every String entry thanks to forClass=String.class.

No need to hack the JSF API/impl. This makes no sense.

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