Java Virtual Machine – JVM

The Java Virtual Machine (JVM) is a critical component of the Java programming language that enables the platform independence of Java programs. It is a software component that executes compiled Java bytecode and acts as an interpreter between the Java program and the underlying hardware.

As an analogy to natural languages that people speak around the world, using Java and a JVM is like “writing everything in English” and then having someone else translate your message to the “specific language that people speak in a particular region”.

The architecture of using a JVM to interpret the Java program code and the JVM itself running on the actual computer system creates important flexibility.

As long as a JVM is available for a computer system, it can run Java programs regardless of that platform’s hardware and operating system.

JVM Origins

James Gosling, the Java programming language creator, introduced the JVM concept. The original idea was to have a single platform-independent language that could run on any computer, regardless of its hardware and operating system.

Naturally, this would make it easier for developers to write software that could run on any platform without worrying about hardware and OS-specific details. This is called WORA, which stands for “Write Once, Run Anywhere”.

Resource Management is Key

While that is a terrific benefit, it creates a challenge for JVM because it requires significant resources to run. It requires sufficient memory and processing power to handle the translating activities, which can limit its use in resource-constrained environments, such as embedded systems and mobile devices.

However, some lightweight versions of JVM, such as Java Micro Edition (Java ME), are designed for use in these environments.

More than just Java

One interesting aspect of JVM is that it is not just limited to the Java programming language. Other languages like Scala, Groovy, and Kotlin can also run on JVM.

Like Java, these languages are also compiled into Java bytecode, which JVM can execute. This makes it possible to write code in these languages that can run on any platform that has a JVM installed.

Conclusion

The JVM is a critical component of the Java programming language that enables platform independence and provides a secure, optimized, and extensible runtime environment for Java applications.

It is highly optimized for performance, supports multiple programming languages, and provides a standard interface for accessing native code.

Although it requires significant resources to run, it remains an essential technology for building large-scale, cross-platform applications.

Overview of JDK, JRE, and JVM – 8 mins