Intro to JAVA

 

JAVA

                    PROGRAMMING LANGUAGE

Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers write once, and run anywhere (WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++ but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as reflection and runtime code modification) that are typically not available in traditional compiled languages. As of 2019, Java was one of the most popular programming languages in use according to GitHub, particularly for client–server web applications, with a reported 9 million developers.

 

 

 

 

History of JAVA

 

·       Begin with project “Green” in 1991 founded by Patrick Naughton, Mike Sheridan & James Gosling who worked for sun microsystems.

 

                     

 

·       The purpose is to draft and plan for future computer programs that can be executed on any machine.

 

·       Firstly it was called “Green talk” by James Gosling and the file extension was “.gt”.

 

 

·       Then it was named “Oak programming language” which was developed in the early 90s by sun microsystems.

 

·       In 1995 java was distributed freely for testing and then the java development kit (JDK) was launched in May 1995.

 

 

·       At present, its developer is Oracle cooperation.

 

 

Java is used for,

• Mobile applications (especially Android apps)
• Desktop applications
• Web applications
• Web servers and application servers
• Games
• Database connection
• And much, much more!

Why Use Java?

• Java works on different platforms (Windows, Mac, Linux, Raspberry Pi, etc.)
• It is one of the most popular programming languages in the world
• It has a large demand in the current job market
• It is easy to learn and simple to use
• It is open-source and free
• It is secure, fast, and powerful
• It has huge community support (tens of millions of developers)
• Java is an object oriented language that gives a clear structure to programs and allows code to be reused, lowering development costs
• As Java is close to C++ and C#, it makes it easy for programmers to switch to Java or vice versa

 

We mentioned about JVM and WORA in our introduction chapter. Let’s see what they are

 

Java compiler

When writing a java programme , the first man made command file cannot be understood by a computer but can be easily read and understood by humans therefore, those codes are called source codes/ human readable codes.

As mentioned these source codes cannot understand by the O/S. To read these codes by computer we use a software named “java compiler”.

Task of the java compiler is read all commands,instructions in the source code and check errors. If there are no errors then creates a new file named “byte code file” as .class file

Java Virtual Machine (JVM)

Even if a byte code file is created as above, it is also not understandable by the computer. Therefore JVM (Java Virtual Machine) has been created for those functions.

A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java byte code. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.

 

Java Runtime Environment (JRE)

The Java Runtime Environment is software that java programs require to run correctly. The JRE is the underlying technology that communicates between the java programme and the operating system.

           

Java Write Once , Run Anywhere (WORA)

Java programmes are platform independent. Platforms means operating systems in a computer. We know the byte code file is read by the JVM and this JVM software various from computer to computer. As a result no matter what operating system is present on your computer the same byte code file will run on your computer as well. This is because of the different types of JVM that are separate for windows, mac OS , Linux etc.  the JVM adopts to the command interpreter of the computer.

This added to an important feature on java termed as portability.

An important point to noted is that while java is platform independent language, the JVM is platform dependent. Different JVMs designed for different OS and byte code is able to run on different OS.

 

Written by

    Sachini Vinodya

    Software Engineering Student,

    (Content Writer at Learn with Panduza).

                            

                                                   Happy learning !