Question

In JSP I can reference a bean’s property by using the tag ${object.property}

Is there some way to deal with properties that might not exist? I have a JSP page that needs to deal with different types. Example:

public class Person {     public String getName() } public class Employee extends Person {     public float getSalary() } 

In JSP I want to display a table of people with columns of name and salary. If the person is not an employee then salary should be blank. The row HTML might look like:

<tr>     <td><c:out value='${person.name}'></td>     <td><c:out value='${person.salary}'></td> </tr> 

Unfortunately if person is not an employee then it can’t find salary and an error occurs. How would I solve this in JSP?

Edit: Is there an instanceof check in JSP tag language?

Answer 1

Just use the EL empty operator IF it was a scoped attribute, unfortunately you’ll have to go with surrounding your expression using employee.salary with <c:catch>:

<c:catch var='err'>     <c:out value='${employee.salary}'/> </c:catch> 

If you really need instanceof, you might consider a custom tag.