Around 25 years ago, on 23rd May 1995, Java appeared as a class based, general purpose and object oriented programming language. James Gosling is known as the designer of Java. Over the last two decades we have seen how Java dominates the IT industry as a static, safe, strong and portable programming language all over the world. Java is now a property of Oracle Corporation, and the latest version (Java SE 15) of java is released on 15th September, 2020. Java programming language gives programmers the opportunity to write once, run everywhere (WORA). It means the portability of this programming language, once a Java code is compiled, you can run that code on almost every platform that supports java. Java Virtual Machine (JVM) plays an important role here, means Java applications are usually compiled into byte code and then you can deploy and execute that code on any JVM regardless of the type of computer architecture. The syntax of Java is comparable to C and C++ programming languages, though Java has limited lower level facilities.
JVM, JDK and JRE
JVM stands for Java Virtual Machine, which is a specially designed engine that facilitates the runtime environment of any application written in Java. Java code is converted to a bytecode, once the code is compiled. One of the key responsibilities of JVM is to convert the bytecode into machine language. JVM is an integral part of JRE (Java Runtime Environment), which means you cannot download JRE separately, and it comes with JRE. Both JDK (Java Development Kit) and JRE are platform dependent, where JVM is platform independent. JVM comes with the collection of a huge number of tools, framework and libraries. JVM has a special feature, known as JIT (Just in Time) compiler, which converts the source code of any java application into a low level machine language. You may consider JVM as the interpreter as it can execute the source code line by line. Basic java functions like Garbage Collection, Memory Management and the security mechanisms are also provided by JVM. JVM is also customizable in terms of memory allocation. Some important components of JVM are class loader, Method Area, Heap, JVM Language Stacks, PC Registers, Native Method Stacks, Execution Engine, native Method Interface and Native Method Libraries.
JDK (Java Development Kit) contains the tools that are required to write programming codes for the applications. JDK includes tools like Java application launcher, Applet viewer, compiler, debugger etc. The compiler in JDK converts the Java code into bytecode and Java Application Launcher calls a JRE to retrieve the required class and execute the main method. All the features of JRE are included in the JDK. JDK can be installed in multiple operating systems like Windows, Mac and Linux OS. Some important components of JDK are Class Libraries, Compilers, Debuggers, JavaDoc and so on.
JRE (Java Runtime Environment) is an application that is designed to run other software. JRE contains Loader Class, JVM and other Class Libraries. It is only the Java programmers, who are required to install JDE on their computer, unless JRE is good enough to run any Java program on the machine. JRE contains Class Libraries, JVM and other supporting files to run a Java application on the machine. JRE also uses important package classes like swingetc, awt, math, lang and other runtime libraries. In order to run java applet, it is required to install JRE on the computer. JRE contains both JVM and Java HotSpot virtual machine clients, incorporated within it. JRE also includes other libraries like Remote Method Invocation (RMI), Java Database Connectivity (JDBC), Java Naming and Directory Interface (JNDI) and so on. Deployment mechanisms like Java Plug-in and Java Web Start are also part of JRE, as well. Some important components of JRE are Class Loader, Byte Code verifier, interpreter, run-time and required hardware.
Java is now one of the widespread programming languages in the IT industry across the world. Some of the most rapidly used Java technologies are:
- Java SE (Standard Edition).
- Java Embedded.
- Java EE (Enterprise Edition).
- Java ME (Micro Edition).
- Java Card.
- Java TV.
- Java Database.
- Developer Tools.
Ten Most Widely Used Domains of Java Application
1. Mobile Applications
Java is one of the most compatible languages for developing mobile apps, as this programming language is compatible with Software Development Kit (SDK), like Kotlin and Android Studio. A major portion of mobile phone users are using Android OS based smartphones, which is one of the key reasons for mobile application developers to choose Java. Android OS has Dalvik Virtual Machine (DVM), in order to execute the class files, which are later wrapped up as Android Application Package (APK). The object oriented approach of Java provides optimum security to android applications.
2. Desktop Based GUI Applications
Java programming language is rich in resources to develop desktop based Graphical User Interface (GUI) applications. Abstract Window Toolkit (AWT), JavaFX and Swing are some among other tools and means to develop Java based GUI applications.
3. Web-based Applications
Web applications are in huge demand in today’s computing and Java programming language has also played its dominating role here, as well. Java comes with supporting tools like JSP, Struts, Servlets and many other similar resources that allow programmers to develop almost any kind of web application, as per the requirement of the organization.
4. Enterprise Applications
Java EE (Enterprise Edition) is the first choice for many application developers to develop enterprise level Application as Java EE provides Application Programming Interface (API) for scripting. This particular edition of Java programming language also incorporates web services and network applications. Java EE is popular for developing applications for financial institutes and large corporations.
5. Scientific Applications
Java has been considered as the first choice among the Application Developers to create scientific applications that require mathematical and scientific operations. Security of such applications is considered as the first priority to the application developers and they are also concerned about the high portability and low maintenance of such applications. MATLAB is one such popular scientific application, which also uses Java for developing an interactive user interface.
6. Gaming Applications
Java also dominates the gaming industry and this high level programming language has the support of Open Source 3D engine. jMonkey is one such Open Source 3D engine that comes with tremendous capacity to develop and deploy 3D games.
7. Big Data Technologies
Big Data is now being considered as part of modern computing. Big Data technology like Hadoop is now being considered as a reality, only because of Java. Some other most widely used programming languages like Scala are a byproduct of the Java programming language. Without any doubt, it can be said that Java is serving as the backbone of Big Data technology.
8. Business Applications
JAVA EE (Enterprise Edition) is made available so that the programmers can develop multi-tiered, large scale, reliable, stable and scalable applications. The development approach of such applications is to mitigate the problems encountered by large corporations and enterprises. Reliability and security are two key features that make such applications more powerful, at the same time the complexity of the development process might increase due to these features. The Enterprise Edition of Java provides a robust development model, API along with a flexible runtime environment that reduces the application development complexity.
9. Distributed Application
Distributed computing and the required platform are dynamic by design. Java programming language comes with the capacity to configure such applications. The software development infrastructure named Java intelligent Network Infrastructure (JINI) is used to provide, locate and register distributed services depending on the specification. JavaSpace is an integral part of Jini, and it supports persistence, migration and distribution of services in a network.
10. Cloud Based Applications
Cloud computing has changed the paradigm of conventional computing. Here, both data and applications are stored in the cloud and the users can have the access to their required resources on a pay-as-you-go basis. In short, cloud computing provides a unique solution to IT infrastructure at a low cost. With the help of Java, developers are ready to build IaaS, SaaS, PaaS and other relevant services, as well.
Job Roles of Java Application Developer
Usually Java Application/software developers are working as:
- Senior Java Developer
- Full Stack Software Developer
- Mobile Application Developer
- Associate Software Developer
- Back End Application Developer
- Mid-Level Software Developer
- Software Engineer
- Java Instructor
Java is a versatile programming language and the salary of a Java application developer depends on the job role, size of the company and business, level/position of the job, and so on. Usually, Java application developers are earning something between £8,519 to £264,115.