JavaBean

The JavaBeans are a component model created by Sun Microsystems for building Java applications.

They are used to encapsulate several objects in a single object (the pod or Bean in English), to make use of a single object instead of several simpler ones.

The Sun Microsystems JavaBeans specification defines them as "reusable software components that can be manipulated visually in a build tool".

Despite many similarities, JavaBeans should not be confused with Enterprise JavaBeans (EJB), a server-side component technology that is part of Java EE.

JavaBean Conventions

To function as a JavaBean class, a class must obey certain conventions about method naming, construction, and behavior.

These conventions allow for tools that can use, reuse, replace, and plug in JavaBeans.

The required conventions are:

• You must have a builder without arguments.
• His class attributes must be private.
• Its properties should be accessible through get and set methods that follow a standard nomenclature convention.
• It must be serializable.

Structure

Within a JavaBean we can distinguish three parts:

• Properties: The attributes it contains.
• Methods: Methods are established get and set to access and modify the attributes.
• Events: Allow to communicate with other JavaBeans.

Example

// Implementation of the Serializable interface of the java.io package public class PersonBean implements java.io.Serializable { // Each instance variable has a private access modifier. private String Name; private int Age; // Empty builder and without arguments. public PersonBean() { ! // Optional builder of a JavaBean. public PersonBean(String Name, int Age) { this.Name = Name; this.Age = Age; ! // Builder per copy (optional) public PersonBean(PersonBean personBean) { this.Name = personBean.getName(); this.Age = personBean.getEdad(); ! // For each property add a get and set method. public String getName() { return Name; ! public void set(String Name) { this.Name = Name; ! public int getEdad() { return Age; ! public void setEdad(int Age) { this.Age = Age; !!