TechFAQ

Step 5. Add Action mapping and form entry into the stuts-confix.xml and validate="true" is for validation framework to validate the form input.

Now in the browser type http://localhost:8080/testApp/EmpForm.jsp

Don't Enter firstName and lastName in the text box and submit the "Save" BUTTON. the RequestProcessor checks for the validateattribute in the ActionMapping.
If the validate is set to true, the RequestProcessor invokes the validate() method of the ValidatorForm instance.
If Validate fail the RequestProcessor looks for the input attribute and return to JSP page mentioned in input tag.
If Validate pass goto Action Class execute() method..
If Validate fail , In the browser (EmpForm.jsp) you can see. In red color.

First Name is required.
Last Name is required.

In the empForm firstName and lastName are the required filed. So in the above configuration you can see we add for both firstName and lastName. You can see depends="required" - "required" property is defind in validator-rules.xml. In the resource bundle : application_resource.propertis file
label.firstName=First Name
label.lastName=Last Name
#Error messages used by the Validator
errors.required={0} is required.
{0} will be filled by (First Name or Last Name) because validation.xml above configuration you have defind
<arg0 key="label.lastName"/>. and <arg0 key="label.lastName"/>.