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Difference Between JDK, JRE and JVM

Last Updated on December 11, 2023 by Ankit Kochar

In the world of Java programming, the terminologies JDK (Java Development Kit), JRE (Java Runtime Environment), and JVM (Java Virtual Machine) hold pivotal roles. Understanding the differences among these components is fundamental for Java developers, as they form the backbone of Java application development. Each serves a distinct purpose in the execution and development of Java-based software.

What is JDK?

JDK stands for Java Development Kit. It is a complete software environment for building applications using Java language. It contains a collection of tools and utilities which are very essential for a developer for writing, compiling, and debugging. The JDK is platform-dependent and because of this reason, it has different OS platform versions for Windows, Linux, Mac, and so on.

The JDK contains the Java Runtime Environment (JRE), which provides the Java Virtual Machine (JVM) for executing Java code. The JDK also contains the Java compiler, which converts our Java source code into Java bytecode that can be executed on any machine that has a compatible JVM in it. The JDK also offers a variety of tools for debugging, testing, and monitoring our Java applications.

Below listed are the features of JDK:

  • JDK provides an environment for writing and running Java source code.
  • JDK provides all the functionalities of JRE and JVM.
  • JDK enables developers in handling exceptions smoothly by integrating many extensions together into a single catch block.
  • It also provides a debugger, compiler, and other development tools.

What is JRE?

JRE stands for Java Runtime Environment. It is a runtime environment that is used for running the java applications in our system. The JRE contains JVM (Java Virtual Machine) along with a set of libraries and utilities that are required in order to run java applications. When we try to execute a java application, a runtime environment is provided by the JRE that contains all the necessary components that are required by the application to execute.

Features of JRE:

  • JRE is a collection of tools that helps in the execution of the JVM. It also provides a few deployment tools like Java Plug-in and Java Web Start.
  • A user can run java code efficiently with only JRE. Unfortunately, JRE does not allow writing java programs.
  • JRE also includes some integration libraries such as JDBC (Java Database Connectivity), JNDI (Java Naming and Directory Interface), RMI (Remote Method Invocation), and others.
  • In addition to JVM, it also contains a virtual machine client for Java HotSpot.

What is JVM?

JVM stands for Java Virtual Machine, and it is a software component that allows your computer to run Java programs. When we write a Java program, it is compiled into bytecode. This bytecode can not execute on its own and requires JVM to run it.

The JVM has the responsibility of executing the bytecode and converting it into machine code that can be understood by the computer. The JVM also manages memory usage and performs garbage collection, which is the process of deallocating memory that is no longer needed by the program.

Listed below are some features of JVM

  • JVM converts byte code into machine code which is understood by the computer.
  • JVM provides fundamental Java functionalities such as management of memory, garbage collection, and so on.
  • JVM uses libraries and files of JRE to run the java program.
  • JVM is an essential component of JRE.
  • It is capable of executing the java program line by line. Hence, it is also referred to as an interpreter.
  • Primary functions of JVM includes program loading, linking, initialization, and compilation.

Difference Between JDK, JRE and JVM

After reading the above introduction of all three components, now we will go through the table below to see the head-to-head difference between JDK JRE and JVM.

JDK stands for Java Development Kit. JRE stands for Java Runtime Environment. JVM stands for Java Virtual Machine.
The Java Development Kit (JDK) is a software development kit that lets you build Java applications. The Java Runtime Environment (JRE) is a software package that includes the Java Virtual Machine (JVM), class libraries, and other components required to run Java applications. The Java Virtual Machine (JVM) is an abstract machine that provides an environment for Java ByteCode execution.
JDK includes tools for creating, monitoring, and debugging Java code. JRE includes class libraries and other supporting files needed by JVM to run Java code. JVM has no software development tools.
It is platform-dependent It is also platform-dependent like JDK It is platform-independent
The JDK mainly assists in code execution. Its primary purpose is development. JRE is primarily tasked with creating an environment for code execution. All implementations are specified by JVM. It is in charge of providing all of these implementations to the JRE.
JDK = Development Tools + JRE JRE = Class libraries + JVM JVM = provides a runtime environment.

In essence, comprehending the disparity between JDK, JRE, and JVM is crucial for any Java developer. The JDK encompasses the complete set of tools needed for Java development, including the JRE, whereas the JRE is an execution environment for running Java applications. On the other hand, the JVM is the runtime instance that executes Java bytecode. Together, these components form a cohesive ecosystem that facilitates Java programming, ensuring seamless development, deployment, and execution of Java applications across various platforms.

FAQs Related to the Difference Between JDK, JRE, JVM

Here are some frequently asked questions related to the differences between JDK, JRE, and JVM.

1. Is the JRE required to run Java applications?
Yes, the JRE is required to run Java applications. When you run a Java application, the JRE provides a runtime environment that includes the JVM and a set of libraries and utilities required for executing the application.

2. Can I run Java applications without installing the JDK?
Yes, you can run Java applications by installing the JRE (Java Runtime Environment). However, if you want to develop Java applications, you’ll need the JDK as it includes the JRE along with additional development tools.

3. How does the JVM facilitate platform independence in Java?
The JVM interprets the Java bytecode generated by the Java compiler. It abstracts the underlying hardware and operating system, allowing Java programs to run on any device or platform that has a compatible JVM installed, thus ensuring platform independence.

4. Are there different versions of JDK, JRE, and JVM available?
Yes, Oracle, as well as other organizations and communities, release different versions of JDK, JRE, and JVM. These versions often include updates, enhancements, and bug fixes to improve performance and security.

5. Is the JDK required on a system where only JRE is needed for running Java applications?
If you only intend to run Java applications and not develop them, installing the JRE suffices. The JDK, which includes the JRE, is necessary only for development purposes.

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