A simple Java object becomes a Java bean when all of the object's data fields are private and are only accessible through methods, known as accessor methods. That's it! These requirements should be followed in object-oriented programming anyway. It's just that JavaBeans forces you to use proper object-oriented programming techniques.
There are also mutator methods, which change the values. The following example shows something that many of us have encountered:
Frame f = new Frame(); f.setVisible( true ); boolean visible = f.isVisible();
The incredibly simple migration from writing Java objects to writing Java beans is no accident. The JavaBeans component architecture is designed so that nearly all of the complexities ...