The Java Developers Kit API
The Java Developer’s Kit is the most fundamental of the Java APIs. The Java Developer’s Kit, comprises a set of classes and interfaces that will help to write applications and applets. This set of pre-existing software is organized into Java packages, also called software libraries. the libraries contain classes to handle the graphical user interface, events, input/output operations, errors and exceptions, system properties, applets, and many other activities. It also consists of some execution files to compile and run Java programs
Javac.exe:
Javac is the Java compiler. This program reads the Java source code files that you prepare with your editor and translates them into executable bytecode files for the interpreter.
Java.exe:
Java is the Java interpreter which implements the Java Virtual Machine. This program reads and runs the bytecode files produced by the Java compiler.
Javadoc.exe:
Javadoc is a tool which generates API documentation in HTML format from Java source code containing automatic documentation generating comments.
Java.lang package
The java.lang package includes elements that define the Java language itself. It also contains two class objects, the Object class and the Throwable class, which form the foundation for classes in other packages.
The fundamental element in Java, the object, the Object class forms the superclass for all other classes in Java library packages.
Java.text
The fundamental element in Java, the object, the Object class forms the superclass for all other classes in Java library packages.
Java.applet:
The java.applet package contains the Applet class, the superclass of all applets, and three related interfaces. The java.applet package enables construction of applets. Classes which extend applet run from within a browser or applet viewer.
Java.util:
The java.util package contains miscellaneous useful classes and methods for accessing the system time and date, and random numbers. Also included is the StringTokenizer class, which is useful for parsing character strings into fields. java.util also defines the Hashtable, Vector, and Stack classes, and includes the Observer interface. java.util must be explicitly imported for code that uses these classes.
Java.lang:
The java.lang package contains classes and interfaces that make up the core Java language.
Also defined are the Number and Math classes, which include the objects: Integer, Long, double, Boolean, and Character. The String and StringBuffer classes are defined in java.lang, as are the Throwable class and Thread class.
Java.net:
The java.net package is for network support, including URLs, TCP sockets, UDP sockets, IP addresses and a binary-to-text conversion.
Java.io package:
The java.io package provides a set of input and output streams to read and write data to files, strings, and other sources.
Java.rmi package:
The java.rmi class library supports Remote Method Invocation between different Java Virtual Machines, which may be running as separate processes on the same system or may be running on different systems connected with a network. RMI permits a client Java program to invoke a method of a server Java program.
