What is Java? Definition, Features, and Components

    A plethora of high-level programming languages is available out there. One of the most widely used high-level, general-purpose programming languages is Java. It is a widely-used object-oriented programming language, which means it is based on the concepts of “objects”, which are basic runtime entities. Not only it is a programming language but also a computing platform for developing robust applications. Well, if you are a newbie to this language and want to explore more about the same, you have landed on the right page. This blog post will make you familiar with the Java language and the computing platform. Also, you will come to know the features and various components of Java. So, let us get started without further ado!

    What is Java ?

    It is a general-purpose, high-level, class-based programming language. It follows the principle of Write Once, Run Anywhere (WORA). Meaning that, once you write and compile a Java program, you can run it on any other Java-enabled machine without recompiling it. This is because the Java programs are compiled into bytecode that can run on any Java Virtual Machine (JVM). The syntax of Java is closely similar to C and C++. Moreover, it is an object-oriented programming language that follows all four concepts, namely polymorphism, abstraction, encapsulation, and inheritance. However, it is not a pure object-oriented language. The reason is Java has primitive data types, such as byte, short, int, long, char, float, double, and boolean, which are not objects. Along with a programming language, Java is also a computing platform. This platform allows developers to write and run Java programs efficiently. It primarily comprises an execution engine, compiler, and set of libraries.

    History

    James Gosling, Mike Sheridan, and Patrick Naughton, in June 1991, began developing the Java language project. Originally, they designed this language for interactive television. However, it was too advanced for the television industry at that time. Initially, the developer, Games Gosling, named the language 'Oak.' He got this idea from an Oak tree that was present in front of his office.  After that, developers named it Green. Finally, Games Gosling renamed the language Java, a type of coffee from Indonesia. While creating this language, the developers had the following five principles:

    • The language must be simple, familiar, and object-oriented.
    • It must be powerful and secure.
    • It must be architecture-neutral and portable.
    • The language must execute with high performance.
    • It must be threaded, dynamic, and interpreted.

    In 1996, Sun Microsystems released the first version of Java, Java 1.0, publicly. Thereafter, the company released many versions of Java with additional and advanced features. However, in 2009-10, Oracle Corporation acquired Sun Microsystems. Today, the Java language is maintained and owned by the Oracle Corporation. The latest version of Java is Java 18, as of March 2022.

    Features

    The following are the salient features of Java:

    • Object-Oriented: Though Java is not purely an object-oriented programming language, it supports all the four basic concepts of OOPS, namely polymorphism, abstraction, encapsulation, and inheritance.
    • Compiled and Interpreted: Java is both compiled and interpreted language. There is a Java compiler (javac) that compiles source code into bytecode. Later, Java Virtual Machine executes that bytecode on any Java-enabled machine.
    • Platform-Independent: As discussed earlier, Java follows the principle of WORA, i.e., Write Once, Run Anywhere. You can write and compile a Java program on one machine and run it on another Java-enabled machine. Therefore, Java is platform-independent. Generally, the Java compiler converts a Java program into bytecode, and that bytecode can run on any Java-enabled platform.
    • Architecture-Neutral: This language is architecture-neutral because there are no implementation-dependent features. For instance, all the primitive data types have fixed sizes. The size of any primitive data type does not change, irrespective of the system architecture.
    • Multi-Threaded: Multi-threading implies the execution of two or more parts of the same program simultaneously for maximum utilization. Java is a multi-threaded language.
    • High Performance: Java is a high-performance language because of its architecture, which reduces overhead during runtime. Also, it comes with a just-in-time (JIT) compiler that compiles code during the execution of a program rather than before the execution.
    • Dynamic: Java is a dynamic language. Meaning that you can load classes in a Java program as and when required.

    Advantages and Disadvantages

    Let us now shed light on some remarkable advantages and disadvantages of Java.

    Advantages

    • Java is a simple-to-use and straightforward language.
    • It supports automatic garbage collection and memory allocation.
    • Since there is no explicit pointer in Java, it is a secure programming language.
    • It is a robust language because it uses strong memory management.

    Disadvantages

    • Java is a slow language since it consumes a lot of memory.
    • It is a bit more expensive than other languages due to its higher processing and memory requirements.
    • You can control Java's automatic garbage collection. And it does not provide functions, like free() ot delete () to free memory.

    Applications

    As discussed earlier, Java is a general-purpose programming language. The following are some of the significant applications of Java:

    • Mobile application development
    • Web-based applications
    • Desktop applications
    • Enterprise software
    • Scientific computing applications
    • Big data technologies
    • Server-side technologies, like Apache, JBoss, and GlassFish
    • Distributed applications
    • IoT applications
    • Gaming applications

    Components of Java Programming

    There are three primary components of Java, namely JRE, JDK, and JVM. Let us discuss each of these components in detail below.

    • Java Development Kit (JDK)

    Java Development Kit (JDK) is a distribution of Java technology and one of the core components of Java programming. It is a software development environment that comprises a set of standard libraries and tools that developers use to build Java applications and applets. Many people get confused between JDK and JRE. If you simply wish to run Java programs on your system, JRE is sufficient. However, if you wish to develop a fully-functional Java software application, you need JDK with JRE. JDK includes the following tools:

    Tools Description
    appletviewer: for java applets Enables us to run Java applets.
    javac: for Java compiler Translates Java source code to bytecode file that Interpreter can understand.
    java: for Java interpreter Runs applications and applets by interpreting bytecode files.
    javap: for disassembler Enables us to convert bytecode files into program descriptions.
    javah: for C header files Produces header files for use with native methods.
    javadoc: for creating HTML documents Creates HTML format documentation from Java source code files.
    jdb: Java debugger Helps to find errors in the program.

    The aforementioned tools are used to build and run Java applications.

    • A Java source code is created in a text editor or an IDE.
    • The Java compiler javac compiles the source code. Later, the Java interpreter java executes the compiled source code.
    • You can check for errors in the source code by debugging it using the Java debugger jdb .
    • The compiled Java program is converted into source code with the help of javap .
    • Java Runtime Environment (JRE)

    Java Runtime Environment (JRE) is a set of components required to run a Java program on a computer. It is a part of JDK and consists of loader classes, libraries, and JVM. JRE is a mandatory component of Java programming if you wish to develop and run Java programs. It comprises of:

    • Java Virtual Machine(JVM) : This interprets the intermediate Java bytecode and generates output.
    • Runtime class libraries: These are a set of core class libraries that are required for the execution of Java programs.
    • User interface toolkit : Toolkits that support varied input methods for the users to interact with the application program. For example, AWT and Swing.
    • Deployment technologies : JRE comprises of following key deployment technologies:
    • plug-in : Enables the execution of a Java applet on the browser.
    • Web Start : Enables remote-deployment of an application.
    • Java Virtual Machine (JVM)

    Java Virtual Machine (JVM) is a virtual machine or a runtime engine that provides an environment to run Java applications. It is part of JRE. Moreover, it takes bytecode from the Java compiler and converts it into machine code. It comprises various libraries, tools, and frameworks. In addition, JVM has a built-in just-in-time (JIT) compiler, which compiles the source code during its execution.

    Types of Java Platforms

    There are four different types of Java Platforms, as follows:

    • Java Platform, Standard Edition (Java SE)

    The API of Java provides all the functionality of Java programming. This type of platform defines everything from the fundamental types and objects of Java programming to high-level classes. Moreover, this platform is ideal to use for networking, database access, graphical user interface (GUI) development, and XML parsing.

    • Java Platform, Enterprise Edition (Java EE)

    This platform, Java EE, is built on top of Java SE. It provides an API and a robust runtime environment for developing secure, highly scalable, large-scale, reliable, and multi-tiered network applications.

    • Java Programming Language Platform, Micro Edition (Java ME)

    The Java ME platform provides an API and a small-footprint virtual machine for running Java applications on small devices, like mobile phones. The API of this platform is the subset of the Java SE API.

    • Java FX

    The Java FX is a robust platform for creating feature-rich internet applications using the Java FX Script. It is a statically-types declarative language. The Java compiler converts programs written in Java FX script into bytecode, and the JVM can run that bytecode.

    Conclusion

    This brings us to the end of our discussion on Java. It is a general-purpose language with a wide range of applications. Thanks to its features and versatility. You can use it for developing a variety of software applications, including mobile, desktop, gaming, and cloud-based applications. Furthermore, Java is majorly used as a server-side technology for back-end development projects. We hope this article has helped you gain in-depth insights into Java. If you have any queries regarding this topic, do let us know in the comments section.

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