Please i request don't give me outdated answers i keep on searching in the Google but my doubt is not clear . Reusable means java bean that is developed in one project can be used in another project right how it is possible to use in another project and what is the difference between EJB and java bean
Well, let's say you are asked to build a GUI using SWING. Now what would happen if you did not have any pre-defined menu-bars, buttons, drop downs, text fields etc? Wouldn't every developer have to write it again and again? That is what you mean by reusable.
Java beans are basically data holders. They are populated by the front end or the database and stored or presented on the other end. The link provided by Campbell above shows how you can write your own beans.
I would not refer a drop-down or a text-field as a Java bean though.
The any class can be re-usable provided the current and future implementations have common purpose for the class. Utility classes are the most re-used components.
EJB's are a whole different thing and they cannot be compared to Java beans. There is no point in finding similarities or differences among these two.