Even the first program we wrote in this book used a library included in the JDK, called a standard library. It is not possible to write a non-trivial program without using the standard libraries. That is why a solid familiarity with such libraries is as vital for successful programming as the knowledge of the language itself.
There are also non-standard libraries, which are called external libraries or third-party libraries because they are not included in JDK distribution, but they are used almost as often. They have long become permanent members of any programmer's toolkit. Meanwhile, keeping track of all the functionality available in these libraries is not as easy as staying abreast with Java itself. That is because IDE gives you a hint about the language possibilities, but it cannot advise about the functionality of a package that...
