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Welcome to Decodejava - An online portal that provides free and easy tutorials of Java programming language.


For an absolute beginner in Java, you may learn Java at DecodeJava in the following sequence, starting with our section Java fundamentals, covering topics such as -

• How to download and install Java
• Setting environment variables for Java
• Executing your Simple Java Program
• Primitive Data types
• Class access modifiers
• Abstract class
• Interface and more.



• Java OOP features - Java includes Object Oriented Programming(OOP) features such as encapsulation, inheritance, polymorphism, method overloading, method overriding and much more. For Java OOP features and more, please begin at Java OOP features.



• Control Statements - Control statements like if, if-else, switch, while loop, break, continue, etc control the flow of our program. To know more about control statements, starting with if statement, please read our section Java Control Statements.



• Java Exceptions- Exception is an unusual exceptional condition or a runtime error, which occurs only during the runtime of a Java program. To know about Java Exceptions and how they are caused in a Java program, you may begin at Exception Handling in Java.



• String - String is a nothing but a sequence of characters within a pair of double quotes. To know about String in Java and its various important methods, please read Java String.



• File Input/Output - File Input/Output classes are used to read data from the files or write data to the files. To know more about file input/output and its important classes, please follow - Java Input/Output classes.



• Thread - A thread is a program in execution that is performing some specific task. Thread is one of the most important features of Core Java and one of the hot topics in the interviews. To know more about Thread and its features, please read Threads in Java.



• Applet - An applet is a Java program that can be transported over the internet and executed by a Java-enabled web-browser. To know more about Applet and its important features, you may read Java Applet Class.



• Collections Framework - Collection Framework provides important interfaces and classes using which we can manage a collection of objects. Collections is an advanced topic of Core Java but you shouldn't miss it. To begin with the classes in Collections Framework, you may go ahead with the ArrayList class at - Collection class - ArrayList.



• AWT and Events- Using AWT package, we can create window based applications and graphical user interface(GUI). User interaction with the elements of a GUI such as a button, checkbox, radio button, or menu of a Java program leads to events. To learn how to handle AWT events, you may begin at Java AWT Events.



• Swing package- Swing framework gives us an ability to create modern window based applications with easy to use graphical user interface(GUI). For more on Swing and its classes with easy code examples, you may begin at Java Swing.





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History of Java Programming Language


Java is a high-level programming language developed by Sun Microsystems. In 1991, a team of engineers called "Green Team" led by James Gosling invented this language while working for Sun Microsystems. Initially, it was named "Oak".



• At that time, it was basically designed to control a list of consumer electronics devices such as - TV Set-top boxes, Cell phones, etc.




• In 1995, Sun Microsystems renamed Oak to Java, with its main focus on contributing towards World Wide Web(www) and internet applications.




• In 2010, Sun Microsystems was acquired by the Oracle Corporation. Significantly, Java is now owned by the Oracle Corporation.







Some useful features of Java



• Simple and easy: Java is based on C++ and anyone who knows C++ will feel easy at learning Java. The syntax of Java is based on C++, excluding the complex/confusing elements of C++ such as - pointers, multiple inheritance and operator overloading. That is why it is also called a simplfied version of C++, which is not only powerful but also easy to use.
  
  


• Reliable: Java's feature like "Garbage Collection" frees a programmer from worrying about the memory management, which wasn't possible with C++. Another feature of Java - Exception Handling, reduces the possibility of a Java application crash, fatal errors and thus boosts its reliability.
  
  


• Secure: The use of Pointers in C++ creates a potential room for bugs, illegal access to memory locations and that's why we don't have Pointers in Java. As Java programs are meant to run in a special environment called- Java Virtual Machine(JVM), Java has made sure that there is no illegal access to the memory locations without proper authorization and thereby avoiding compromising with data integrity.



• Object Oriented: Java is an object-oriented language. All the program code, data and methods/functions reside in the form of objects and classes. Many features of OOP(Object Oriented Programming) paradigm are also present in Java, such as :
  a) Object and classes
  b) Encapsulation
  c) Inheritance
  d) Polymorphism
  If you are not aware of these terms, don't worry! We will discuss these features in detail in the upcoming articles, later on.
  
  


• Multithreading: Multithreading is a special feature of Java, enabling a programmer to make programs that are able to do multiple tasks at the same time or at least giving an impression of being multiple tasks being executed at the same time, in a very smooth and interactive manner.
  
  


• Platform independent/Portable: A compiled code of a Java program can run on any platform i.e. on any operating system or hardware. Once a Java program is compiled, it runs into an environment called - Java Runtime Environment(JRE), which contains Java Virtual Machine(JVM) and a special set of libraries which are needed for the proper execution of a Java program.
  
  This special runtime environment or JRE is available for all the platforms like Linux, Mac, Windows, etc. For example, we can write our program on a Linux machine, compile it and once compiled, we can execute this program on any Windows or Mac machine. This gives portability boost to Java programs and makes them platform independent.



In the next article, we are going to learn how to download and install the Java Development Kit(JDK), JDK is a software development required to develop and execute Java programs. So buckle up your seat belts, as we are off to a great ride!





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