What is Java? Overview of the Java Programming Language

Java is a popular and modern programming language used to develop a wide range of applications, including games, database management systems, IoT applications, cloud computing, and artificial intelligence.

In this article, Recruitery will guide you through understanding “what is Java?”, its outstanding features, advantages and disadvantages, the operating principles of Java, and how to program in Java.

What is Java?

 what is java

Java is a popular programming language. Source: Hanoi Vietnamese American College

At the beginning of this article, we will explore what Java is. Java is a widely-used programming language in various fields such as:

  • Web development
  • Mobile applications
  • Embedded systems
  • Artificial intelligence

Java is designed to be simple, secure, portable, and cross-platform. Furthermore, it is an object-oriented language that allows programmers to create objects with distinct properties and methods.

Applications of Java

a computer screening language program

Java has many different applications. Source: FPT Shop

In addition to learning about what Java is, it's important to understand its applications. Java is a versatile and general-purpose programming language used to develop various types of applications. Here are some examples of applications written in Java:

Game Development

Java is one of the most popular programming languages in the field of game development. It can be used to create 2D and 3D games for a variety of platforms, from personal computers to mobile phones to handheld devices. 

For example: Minecraft, Runescape, Angry Birds, and Plants vs. Zombies.

Database Management Systems

Java is used to develop database management systems (DBMS), which store, process, and retrieve data. Java can connect to various types of databases, including relational databases (SQL) and non-relational databases (NoSQL). 

For example: Oracle Database, MySQL, MongoDB, and Apache Cassandra.

IoT Applications

Java is suitable for developing IoT applications because it is cross-platform, secure, and high-performance. It can be used to create IoT applications for devices such as embedded computers, mobile devices, wearable devices, and home appliances. 

For example: Smart Home, Smart City, Smart Car, and Smart Watch.

Cloud Computing

Java is a suitable programming language for developing cloud computing applications, including Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). 

For example:  Google App Engine, Amazon Web Services, Microsoft Azure, and Netflix.

Artificial Intelligence

Java is suitable for developing artificial intelligence applications, supported by libraries and tools for big data processing, analysis, and machine learning. 

For example: Weka, Apache Mahout, Deeplearning4j, and Stanford CoreNLP.

Outstanding Features of Java

features of java

Java possesses many outstanding features. Source: FPT Shop

Beyond understanding what Java is and its applications, Java boasts many outstanding features, making it one of the most popular programming languages today. Here are some of its remarkable features:


Java is a cross-platform programming language that can run on various operating systems and devices thanks to the Java virtual machine (JVM). Java applications can run on Windows, Linux, Mac OS, Android, iOS, and more without altering the source code.

Automatic Memory Management

Java eliminates the need for manual memory management by employing a garbage collector to automatically remove unused objects from memory, reducing memory-related errors.

Multi-threading Support

Java enables the creation of programs that run multiple tasks in parallel, known as threads, enhancing performance and responsiveness.

High Security

Java is designed with robust security measures, restricting direct access to system memory and verifying source code or executable files before execution.

Supports Powerful Libraries and Development Tools

Java offers a rich ecosystem with numerous libraries and development tools, simplifying application development and enhancing functionality.


Java can convert programs into platform-independent executable files (JAR files) that can run on any computer with a JVM installed.

Platform Independence

Java relies only on JVM to run programs, making it highly compatible with various devices.

Inheritance and Polymorphism

Java is an object-oriented language that supports inheritance and polymorphism.


Java allows the creation of new features or improvements to existing features using mechanisms such as interfaces, abstract classes, abstract methods, or virtual methods.

Advantages and Disadvantages of Java

When learning about what Java is, it's essential to consider its advantages and disadvantages. While Java offers many excellent features, it is not without its drawbacks. Here are some pros and cons of Java:


  • Easy-to-understand Syntax: Java's syntax is easy to grasp and similar to C and C++ languages.
  • Rich and Powerful Library: Java provides extensive libraries with a wide range of functions and features.
  • Java Virtual Machine (JVM): The JVM enables running Java programs on multiple operating systems without changing the source code.
  • High Security: Java's security measures prevent direct access to computer memory.
  • Multi-threading: Java supports multitasking within a single program.


  • Performance: Java's performance is lower than that of compiled languages like C and C++ due to its reliance on the JVM.
  • File Sizes: Java applications tend to have larger file sizes due to additional libraries and support classes.
  • JVM Dependency: Java programs rely on the JVM, which can pose issues if the JVM has problems or is incompatible with the operating system.
  • Handling Real Numbers: Java's handling of real numbers using float and double data types may be less precise compared to other languages.

Java's Operating Principle

When learning about what Java is, you've likely encountered the principle of "write once, run anywhere." In Java, source code is compiled into bytecode, which is a platform-independent form of machine code. 

This bytecode is then interpreted by the Java virtual machine (JVM), which simulates a virtual computer. The JVM converts bytecode into machine code suitable for the computer's operating system, allowing Java programs to run on various platforms without source code modifications.

How to Program in Java

To program in Java, you'll need the following tools:

  • A source code editor (e.g., Notepad++, Sublime Text, Visual Studio Code).
  • A Java Development Kit (JDK) containing the Java compiler (javac) and the Java virtual machine (JVM).
  • An Integrated Development Environment (IDE) like Eclipse, NetBeans, or IntelliJ IDEA (optional).

The basic steps for programming in Java

1. Write Java source code in a source code editor and save it with a .java extension.

2. Compile the source code using the Java compiler (javac) to create a bytecode file with a .class extension.

3. Run the program using the Java virtual machine (java) by specifying the bytecode file name.


Java is a modern, powerful, and flexible programming language widely used in various fields. We hope this article from Recruitery has helped you understand what Java is and gain an overview of the Java programming language. Good luck with your Java journey!