The Java Bean ?

[sde]

is a bean just a class in your project?

i'm having trouble getting a jsp app to work.

i made a class in the WEB-INF/classes dir.

it's a simple user class. username , email

in my jsp, i am calling it like this:

<jsp:useBean id="mybean" class="User" scope="session" />
<jsp:setProperty name="mybean" property="username" value="sde" />
<jsp:setProperty name="mybean" property="email" value="me@somewhere.com" />

i get an error that says: 'User mybean = null'

am i going about this the right way?

[Belisarius]

Is the bean in a package? I've always packaged my beans.

[technobard]

Does your class have public getter and setter methods? You'll need those to interact correctly with the get and setProperty tags.

[sde]

i can't just declare the properties in the class public?

[technobard]

No. To act properly as a javabean, you need public getter and setter methods.

[technobard]

A little more info:
The bean specification examines the class and expects certain naming conventions to figure out which properties are available, etc.

Your class should look something like:

public class User {
    String username="";
    Strimg email="";

    public User() {
    }

    public String getUsername() {
       return username;
    }

    public void setUsername(String username) {
       this.username = username;
    }

    public String getEmail() {
       return email;
    }

    public void setEmail(String email) {
       this.email = email;
    }
}

If I remember correctly, the getter and setter methods must be named by using the prefixes "get" and "set" followed by the variable name with the first letter capitalized.

[sde]

ok .. so the properties aren't really 'username' from the bean's perspective? it is 'getUsername' .. that sorta makes sense.

although it would be nice if i could just declare username public and access it. hehe, i'm sure there's a good reason.

thanks

[Belisarius]

It's generally considered good form in Java to access an object through methods rather than public fields. You could access a public field in a bean by doing <%=object.field%>, but depending on whom you talk to, it's better to use the tags in order to keep seperation between the parts of MVC.

Why they chose this particular route for the get/setProperty tags was probably due to the fact that your get/set methods might be more complex than just referencing a String variable (you might access a database), at which point referencing a field won't do you a lot of good.