Java Introduction

Java is a programming language and a platform developed by James Gosling at Sun Microsystems (which has since been acquired by Oracle) and released in 1995.

Java is a high level, robust, object-oriented, class-based, concurrent, secured and general-purpose computer-programming language. It is a widely used robust technology.

For executing any java program, you need to

  • Install the JDK if you don’t have installed it, download the JDK and install it.
  • Set path of the jdk/bin directory.
  • Create the java program (.java file name)
  • Compile and run the java program


Simple Java Example:-


Parameters used in this Java Program

  • class keyword is used to declare a class in java.
  • public keyword is an access modifier which represents visibility. It means it is visible to all.
  • static is a keyword. If we declare any method as static, it is known as the static method. The core advantage of the static method is that there is no need to create an object to invoke the static method. The main method is executed by the JVM, so it doesn’t require to create an object to invoke the main method. So it saves memory.
  • void is the return type of the method. It means it doesn’t return any value.
  • main represents the starting point of the program.
  • String[] args is used for command line argument. We will learn it later.
  • System.out.println() is used to print statement. Here, System is a class, out is the object of PrintStream class, println() is the method of PrintStream class. We will learn about the internal working of System.out.println statement later.

To compile and run this program, you need to open the command prompt in windows by

start menu -> All Programs -> Accessories -> command prompt

Compile the above code using the command:-


When we compile Java program using javac tool, java compiler converts the source code into byte code.

Execute the above code using the command:-

java HelloJava