Java – what is the point of beans?

• Java

I have some JSP tutorials for beans. I don't understand what a bean class is All is to get and set methods Why use them?

public class UserData {

String username;
String email;
int age;

public void setUsername( String value )
{
    username = value;
}

public void setEmail( String value )
{
    email = value;
}

public void setAge( int value )
{
    age = value;
}

public String getUsername() { return username; }

public String getEmail() { return email; }

public int getAge() { return age; }

}

And JSP are

<jsp:useBean id="user" class="user.UserData" scope="session"/> 
<HTML>
<BODY>
You entered<BR>
Name: <%= user.getUsername() %><BR>
Email: <%= user.getEmail() %><BR>
Age: <%= user.getAge() %><BR>
</BODY>
</HTML>

Solution

>Bean gets all the benefits of Java's "write once, everywhere" paradigm

> Advantages of Bean

More than a decade ago, using scriptlets (these <%% > things) was really discouraged because of the birth of taglibs (such as JSTL) and EL (expression language, those ${}) The main disadvantages of scriptlet are:

>Reusability: you cannot reuse scriptlets Replaceability: you cannot abstract scriptlets. > OO capability: you cannot use inheritance / composition. > Debuggability: if the scriptlet throws an exception halfway, all you get is a blank page. > Testability: scriptlets are not unit tested. > Maintainability: it takes more time to maintain mixed / chaotic / repetitive code logic

> Check Whole…BalusC’s answer here

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