Udemy Online Java Training Courses

java-user-inputJava is an object-oriented language developed in the year 1995, by Sun Microsystems. Since then, Java has evolved as one of the most widely implemented language for software development purposes. Java is secure, robust, reliable and efficient at the same time. Java first introduced the famous WORA (Write once run anywhere paradigm) principle that brought revolution in software development arenas. Java fosters WORA by providing a Java Virtual Machine which is capable of running Java byte code compiled on any platform. This eliminates the need for platform specific compilation. There are thousands of online Java training resources available for novice to professionals. This article introduces some of the basic concept of the Java language along with some useful online Java training resources.

For beginners, Udemy has several online Java training courses.

A basic Java Program

The following example demonstrates some of the most basic principles of a Java application. This is a basic Java application that is good enough to comprehend the compilation flow and syntax of Java.

public class MyClass {

public static void main(String[] args) {

System.out.println("Welcome to Java.");



The above Java application does nothing except printing a string of characters on the console output, yet it is sufficient enough to understand how a Java code is actually written and executed.

All functionality of a Java application is encapsulated inside a class. Anything which has some properties and can perform some function is candidate of being implanted as a class in Java.

Methods and Variables in Java

The properties of a class are encapsulated via variables and the functionalities of a class are encapsulated via methods. The following example demonstrates the concept of methods and variables in Java.

public class MyClass {

int number = 10;

public void displayNumber()




public static void main(String[] args) {

MyClass mc = new MyClass();




Here, the MyClass contains a member variable named number with value 10. A method named displayNumber has been implemented which displays this number. So, a variable is referring to a property of the class which is number and method is referring to the functionality of the class that it can displayNumber.

Java Code Compilation strategy

Java code compilation is different than the preceding programming languages like C, C++, COBOL and PASCAL etc. In Java, compilation is different. Instead of directly compiling the Java code into machine specific instructions, the Java compiler compiles the Java code into Java byte code which is not exactly machine instructions.

Java byte code is independent of the machine on which it will run. JVM (Java Virtual Machine) is an abstraction layer between the Java byte code and the underlying hardware. The JVM has different version for different platforms. Java byte code is translated into machine instructions by this Java virtual machine.

This JVM feature allows developers to write Java code without worrying about the platform on which the code will run. Java code that has been written once can be run on Linux operating system via Java virtual machine for Linux, the same code can be executed on Windows operating system and also for other operating system. This Java feature has helped Java beat most of its other competitors since they develop machine specific code that has to be altered if it has to be executed on other operating systems.

Coming back towards the online Java training courses that can help beginners and expert programmers hone their Java skills, Udemy contains several online courses both for Java beginners and for experts.

Java GUI development with Swing

Most of the advanced software applications in the recent times come with an aesthetic GUI. For this reason, Oracle has developed a set of Java Foundation Classes that help developers implement complex GUI without having to write everything from bits and pieces. The Java Swing library is a set of GUI tools that can be used to render complex graphical user interfaces with ease of use.

Before SWING, Java used abstract window toolkit (AWT) which provides intrinsic look and feel for the GUI based controls. However, the Swing toolkit revolutionized the way graphical user interfaces are rendered in Java. The GUI components in the Swing toolkit are extremely flexible in the way in which they are displayed. They adopt the look and feel of the GUI components of the operating systems on which they are being run.

For instance, if a GUI based Java application is run on Linux operating system, the components would adopt the default look and feel of the Linux GUI controls. On the contrary if the same GUI based application is deployed on the Windows based operating system, the look and feel of the controls would be altered to adopt the look and feel of the default GUI controls of the Windows OS. This demonstrates the flexibility of Java Swing components in rendering GUI based components.

Java Swing toolkit is such a vast domain in itself that several online java training courses have been dedicated purely to it. As always, Udemy contains several such tutorials that explain the Java Swing toolkit right from the scratch.

One such online Java tutorial on Swing toolkit. This video tutorial explains in detail the process of developing complex GUI based application using Java Swing library.

Java for Android

One of the most fascinating aspects of Java language is that it is one of the languages that power the famous android application development for mobile operating systems. Android is one of the most booming mobile operating system and a sound knowledge of Java can help developers easily convert to android application development domain. Android uses Linux kernel for development. Java, along with Linux provides a perfect combination for developing robust and reliable android applications.

Udemy offers number of online java training courses for developing android based applications. These tutorials are extremely affordable with some of the best developers teaching the tricks of the trade. One such online java training video courses is available here. This course explains the concept of android application development with Java from the scratch.