Java API

The Java API is what makes Java attractive and useful. It consists of a set of packages that are distributed with the JDK as class libraries. These packages provide a common interface for developing Java programs on all Java platforms. The Java API furnishes all the capabilities needed to develop console programs, window programs, client and server networking software, applets, and other applications. It is the difference that takes Java from being a really good programming language to making it a very powerful and efficient programming environment.

The Java API consists of eight major development packages and a supporting debug package,Packages are collections of related objects. For example, there are separate packages for developing window programs, applets, and networking software.

Java packages contain classes, interfaces, and exceptions

Classes form the basis for object-oriented software development in Java. They contain variables and methods. Variables are data containers. Methods implement operations on the class and its variables.

Interfaces are collections of related methods. An example of an interface is the DataInput interfacee of the java.io package. It specifies a collection of methods that must be defined for a class to implement the DataInput interface. Exceptions are events that alter the normal course of program execution.