Java Environment:

Java environment includes a large number of development tools and hundreds of classes and methods. The development tools are part of the system known as Java Development Kit (JDK) and the classes and methods are part of the Java Standard Library (JSL), also known as the Application Programming Interface (API).

1) JAVA DEVELOPMENT KIT:

The Java Development Kit comes with a collection of tools that are used for developing and running Java programs. They include:

• appletviewer (for viewing Java applets)

• javac (Java compiler)

• Java (Java interpreter)

• javap (Java disassemble)

• javah (for C header files)

• javadoc (for creating HTML documents)

• jdb (Java debugger)

The following table describes the tools used in java environment

appletviewer	it enables us to run java applets (without actually using a java-compatible browser).
java	java interpreter, which runs applets and applications by reading and interpreting bytecode files.
javac	the java compiler, which translates java sourcecode to bytecode files that the interpreter can understand
javadoc	creates html-format documentation from java source code files,
javah	produces header files for use with native methods.
javap	java disassembler, which enables us to convert bytecode files into a program description,
jdb	java debugger, which helps us to find errors in our programs.

The way these tools are applied to build and run application programs is illustrated in the figure below. To create a Java program, we need to create a source code file using a text editor. The source code is then compiled using the Java compiler javac and executed using the Java interpreter Java, The Java debugger jdb is used to find errors, if any, in the source code. A compiled Java program can be converted into a source code with the help of Java disassembler javap.

2) APPLICATION PROGRAMMING INTERFACE (API):

The Java Standard Library (or API) includes hundreds of classes and methods grouped into several functional packages. Most commonly used packages are:

• Language Support Package: A collection of classes and methods required for implementing basic features of Java.

• Utilities Package: A collection of classes to provide utility functions such as date and time functions.

• Input/Output Package: A collection of classes required for input/output manipulation.

• Networking Package: A collection of classes for communicating with other computers via Internet.

• AWT Package: The Abstract Window Tool Kit package contains classes that implements platform-independent graphical user interface.

• Applet Package: This includes a set of classes that allows us to create Java applets. The use of these library classes will become evident when we start developing Java programs.