Java in this context is a class-based, object-oriented programming language and one of the most popular languages in the world. Together with the Java Development Kit (JDK) and the Java Runtime Environment (JRE) it forms the Java Technolgy. The runtime itself consists of several libraries and the Java Virtual Machine (JVM). It is important to know that the JRE can not only run bytecode compiled from Java but also from other programming languages like Scala, Groovy, or Kotlin (and theoretically from any other languages if a bytecode compiler exists for them).
Java applications are written in a form that humans can understand, the so-called source code. This source code cannot be run directly and needs to be compiled by the Java Compiler, which is part of the JDK, into bytecode that computers can understand. The machines running the bytecode are typically virtual machines. This means that the code isn't directly run by the hardware but by software on the target platform. This virtualization enables platform-independence, a big feature of Java. Applications written in Java can run on almost any device and computer architecture if a corresponding runtime environment is installed.
Java was originally invented by James Gosling in the early 1990s during his time at Sun Microsystems because he was not satisfied with the capabilities of C++. The first prototype was called Oak (Object Application Kernel) and it was targeted towards interactive television and other entertainment devices. The original compiler was written in C and shortly after the language was renamed to Java and the focus shifted to the World Wide Web.
Since 2010 Java belongs to the Oracle Corporation as part of the acquisition of Sun Microsystems.
In general, the programming language Java is used to write code in a human-readable way that gets compiled into bytecode that runs on virtual machines on any kind of device. Especially with the rise of the Internet-of-Things, the numbers have skyrocketed. In fact, Java runs on billions of devices today. Due to its nature of being platform-independent, Java is also used for many applications.
Here are some examples:
- API backends
- Machine Learning backends
- Storage backends
Processing backends in the financial industry
Native Android Applications
Industrial Control Systems
Big corporations use Java as a fundamental piece of their tech-stack. For example, most of Amazon's stack including AWS is based on and written in Java.
Java as a programming language - as already said before - is used to write programming code that gets compiled and executed on machines. Java on your computer (and what this question often refers to) means the Java Runtime Environment, the JRE. It does nothing on its own but provides the infrastructure to run Java-based applications on your local computer or on virtual machines distributed over a network.
This question often relates to the question if you need to install Java on your computer. While it is not necessary to have it installed in general, many applications today rely on the Java Runtime Environment to function. So, if you want to install an application that is written in Java - yes, you need to install the Java Runtime Environment. But you don't need to install the JDK or have knowledge of the Java programming language for that! The main reason to know about the programming language Java is if you want to become a Java developer.
A Java Developer is a software developer or engineer that specializes in or has some decent knowledge of the Java programming language to use it for writing applications with it. This can either be professional as part of their daily work or just as a hobby. Because Java is mainly used for writing server-side applications (the back-end) people are often referring to Java Developers as Backend developers.
Because many corporations all over the world use Java as a part of their tech-stack and the language itself is very popular, Java Developers are in high demand and in general well-paid.
- What language is the best for the project or company?
- Do I want to work on the client-side, server-side, or both (as a full-stack developer)?
- How many resources like learning materials, tutorials, courses, libraries, frameworks, etc exist for the languages?
Here is a great video for you that also explains some of the key differences!
This post was originally published on The Smart Coder by my friend Ann Fraser.
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