import java.lang.*;
public class First
{
public static void main(String[] args)
{
System.out.println("This is my first Java program.");
}//end main
}//end class
The statements have the following meaning:
• import java.lang.*;
request to use libraries of predefined classes/programs
(in fact, the java.lang library is imported automatically, hence this statement can be omitted)
• public class First {...}
definition of a class/program called First
• public static void main(String[] args) {...}
definition of the main method
(a method is the realization of an operation in Java)
• System.out.println("This is my first Java program.");
statement to print a message on the video
• System.out
predefined object/instance of the predefined class PrintStream
• println
method of the class PrintStream applied to the object System.out
• "This is my first Java program."
object of the class String representing the sentence to display
In this course we will use the Java programming language. Java is a modern, high level, object oriented programming language, which supports also the imperative and the functional programming paradigms.
General characteristics of Java:
• simple
• platform independent (the same program can be run on Windows, Unix, MacOS, etc.)
• comes equipped with a very rich set of well developed libraries
• designed for the use on Internet
• based on virtual machine (see later)
• safe (the virtual machine forbids undesired accesses to applications running via the Internet)
Updated: Friday, July 24, 2020 5:18 PM