Introduction to Java

Java

• Developed by James Gosling, Arthur Van Hoff and Andy Bechtolsheim.
• Original name “oak”.
• Developed by Sun microsystem.

Features of java

• Robust
• Platform independent
• Freely available
• Secure
• Object-oriented

Types of Java programs

• Internet Applet
• Stand-alone application

Stand-alone Application

These applications need external support like the internet.

Internet Applet

These applications do not need internet support.

Java Byte Code (JBC)

The code converted by the Java compiler is known as Java byte code. It is an intermediate code that is neither machine-dependent not platform dependent.

Java Virtual Machine (JVM)

It is a machine that converts source code into java byte code.

Java development kit (JDK)

It is a collection of Java development tools.

Java APIs

API stands for application program interface which is a collection of pre-compiled codes.

Structure of a java program

Documentation section

This section is used to giving comments. It is an optional section comment can be given in two ways:

• Single line comment – / /
• Multi-line comment – /*——————*/

Package section

In this section, packages are imported. This is also an optional section.

Package

It is a collection of classes

Class definition

In this session, class is defined.

Main section

It is a compulsory section in which the functionality of a program is described.

IDE

It is an IDE (Integrated Development Environment) developed for oops.

 

Features of Blue J

• GUI
• Fully integrated environment
• Graphical and textual editing
• Object-oriented
• Built-in edition, debugger, etc.

Jar files

It is an executable file of a JAVA project. It can be executed by double-clicking on its icon.

What is the purpose of a new operator?

The purpose of the new operator is to create objects.

What is the use of keyword import?

The use of Keyword import is to include the package.