Java Runtime Environment

Purpose of Java Runtime Environment

Whenever a program is sent for execution, the Java Runtime Environment combines the libraries and JVM to compile the program and build the Byte Code. It combines all the resources for the execution of the program. It actually exists as an implementation of Java Virtual Machine.

It can be summed up and said JRE = set of libraries + other files that JVM uses at runtime.

How does JRE work?

• JRE provides the runtime environment for executing Java bytecode
• When you run a Java program:
  • JRE loads the class files
  • Verifies the bytecode for security
  • JIT compiler converts bytecode to native machine code
  • Manages memory allocation and garbage collection
  • Provides access to libraries and APIs
  • Handles runtime errors and exceptions

What does JRE consist of?

The components of JRE are:

• Java Virtual Machine (JVM):
  • Class Loader
  • Runtime Memory Areas
  • Execution Engine
  • JIT Compiler
  • Garbage Collector
• Core Classes and Libraries:
  • Java API packages
  • Language support classes
  • Utility classes
• Runtime Support Files:
  • Property settings
  • Configuration files
  • Integration libraries
• Development and Deployment Tools:
  • Basic tools for running applications
  • Security managers
  • Integration plugins

Developmental Tools

JRE consists of some popular developmental tools which help to create applications easier. Some of the tools are:

• Standard JDK Tools and Utilities
• Javac, Javadoc
• Internalisation tools
• Remote methods
• Java development tools
• Java plug in tools
• Java web start tools

Why to use Java Runtime Environment?

Well, for developers, JDK is most important, as it will also include JRE and other classes but if we have to just run some program in java then we can use only JRE for the purpose. We do not need to install the heavy development kit rather we can just install JRE.

How to Install of Java Runtime Environment?

If you want to install JRE in your local environment then follow the below steps:

• Browse to Java SE Runtime Environment 9 download page and choose the JRE installer.
• Download any of the latest JRE installers.
• Click on Accept License Agreement and then select the corresponding windows version and install it.

You can also checkout the official JRE documents on the link.

Difference between JVM, JDK, and JRE

Frequently Asked Questions

Is it always necessary to have Java Runtime Environment to run a java programme?

JRE provides the basis for execution of a java program, without it any Java code cannot be executed.

Can we use JDK instead of specifically downloading Java Runtime Environment?

Yes, Installing JDK is much better for developers as it also includes JRE and other classes for programme execution.

Is JVM a physical programme?

JVM is not a physical program like JRE or JDK, but it is associated with JRE and JVM will always require the recourses compiled by JRE to execute a programme.

Which Java environment is best?

The best Java environment depends on your needs: for development, the JDK is essential, while for running applications, the JRE suffices. The JVM is crucial for executing Java code across platforms. Choose based on whether you're developing or just running Java applications.

Conclusion

Java plays a vital role in most application development in these days and hence JRE will always come into picture for the execution of any Java program. Even now billions of devices use Java for their primary functionalities, JRE being an essential component of the Java Development architecture.