Java Runtime Environment

27 MARCH 2020 • 6 MIN READ

Paweł Baczyński



Java Runtime Environment header picture


The Java platform comes with three key components: the Java Development Kit (JDK), the Java Virtual Machine (JVM), and the Java Runtime Environment (JRE). They’re a must-have in any project based on developing and running Java applications.

What is the Java Runtime Environment?

The Java Runtime Environment is software designed to help developers run other pieces of software. When developers need to execute a software program, they need an environment to run in. The runtime environment is responsible for loading class files and ensuring that the program can access memory and other system resources.

The Java Runtime Environment is a software layer that runs on top of a device’s operating system and provides additional services that are specific to Java. The runtime environment for Java includes the Java class libraries, Java class loader, and Java Virtual Machine (JVM).

The class loader helps to correctly load classes and connect them to the core Java class libraries. Developers use the JVM for ensuring that their applications have the resources they require to run and perform well in devices or cloud environments. What about the JRE? It mainly acts as a container for the other components (and orchestrates their activities).

Benefits of Java Runtime Environment

Versatile operating systems

Thanks to JRE, developers can blur the diversity between different operating systems, ensuring that their software runs on any OS without modification.

Automatic memory management

One of the most important value-added services of JRE is automatic memory management. This ensures that developers don’t need to control the allocation and reallocation of memory manually.

Integration libraries

The JRE includes integration libraries such as Java Database Connectivity and Java Naming and Directory Interface.

java logo

Java memory

Java memory is made of three components: the heap, stack, and metaspace (called permgen until Java 8). The metaspace is where Java keeps the program's unchanging info (for example, class definitions). Heap space is where you’ll find variable content. Java stores function execution and variable references in the stack space.

Since Java 8, developers can take advantage of metaspace which introduced a significant change in how developers interact with the memory space of this programming language. Before, they would have to use the command java -XX:MaxPermSize to monitor the size of the space available in permgen. From Java 8, the technology is able to automatically increase the size of the metaspace to accommodate the meta-needs of software. Java 8 also introduced a brand-new flag called MaxMetaspaceSize, which development teams can use to limit the metaspace size.

Java application monitoring

Application monitoring is primarily a function of the Java Virtual Machine. However, the JRE also provides a range of configuration options that form the foundation for monitoring. Developers can use a variety of tools for monitoring Java applications, from simpler ones like the Unix command top to sophisticated solutions for remote monitoring (such as Oracle's infrastructure monitoring).

Moreover, programmers also get to benefit from visual profilers like VisualVM that allow inspecting a running JVM. Thanks to all of these tools, a development team can identify and track down hotspots and memory leaks, and monitor the overall memory consumption of your system.

Hire Java developers

Are you looking for an experienced team of Java developers for your project? Do you need help in expanding your product with extra Java skills on board? Get in touch with us. We help companies all over the world to make the most of this incredibly powerful technology and realize their business goals efficiently.