JDK Vs JRE Vs JVM – How Are They Different from Each Other?

JDK Vs JRE Vs JVM – How Are They Different from Each Other?

As a Java developer, you need to understand the difference between JDK, JRE, and JVM before moving ahead with Java application development. So, being a leading Java development company we have compared JDK vs JRE vs JVM and how they are different from each other.

So, let’s begin!

JDK vs JRE vs JVM – A Brief Overview

JDK

JDK stands for Java Development Kit. It is a software development environment used for developing Java applications and applets. JDK exists physically and includes JRE and development tools.

It is an implementation of any of the following Java Platforms introduced by Oracle Corporation:

• Standard Edition Java Platform
• Enterprise Edition Java Platform
• Micro Edition Java Platform

The JDK has a private Java Virtual Machine (JVM) and other resources including an interpreter or loader (java), a compiler (javac), a documentation generator (Javadoc), an archiver (jar), and more for the completion of the Java app development.

JRE

JRE is a short form of Java Runtime Environment. It is also abbreviated as Java RTE. The Java Runtime Environment is a rich set of useful software development tools for Java application development. It is the implementation of JVM and is used to provide the runtime environment. It exists physically and comes with a set of libraries and a few other files used by JVM at runtime.

The JVM’s implementation is also released by other companies along with Sun MicroSystems.

JVM

Java Virtual Machine or JVM is an abstract or virtual machine because it does not exists physically. JVM is a specification that provides a runtime environment where Java bytecode is executed. It can also execute programs written in other languages and compiled to Java bytecode.

JVMs are available for numerous hardware as well as software platforms. All of the three – JVM, JRE, and JDK are platform-dependent because each OS has a different configuration.

However, Java is platform-independent, there are 3 concepts of the Java Virtual Machine – Specification, Implementation, and Instance.

JDK vs JRE vs JVM – Why Should You Use?

JDK

Here are some of the major reasons why a Java development company or developer should use JDK:

• JDK has useful tools to write Java programs and Java Runtime Environment that run the written program.
• It has a compiler, Appletviewer, and Java application launcher, and more.
• The compiler translates the Java program into bytecode.
• Java application launcher opens a JRE, loads the essential class, and runs its main method.

JRE

Below are the key reasons to use JRE:

• JRE has class libraries, JVM, and a few supporting files. It does not have any tool for Java application development like the compiler, debugger, etc.
• It utilized necessary package classes such as math, util, swingetc, lang, awt, and runtime libraries.
• You need to install JRE in your system to run Java applets.

JVM

The following are the main reasons why a Java development company should use JVM:

• JVM has a platform-independent way of running Java source code.
• It contains many tools, libraries, and frameworks.
• After the Java program is executed, it can be run on any platform which saves a significant amount of time.
• JVM has JIT (Just-in-Time) compiler that turns Java source code into low-level machine language. This makes it run faster as a regular application.

JDK vs JRE vs JVM – Key Components

JDK

Following are the key components of JDK:

• JDK and JRE – A Java developer uses JDK to write a Java program that can be executed by the JRE which includes JVM and class libraries.
• Class Libraries – It is a collection of dynamically loadable libraries which are called by the Java program at runtime.
• Compilers – This Java program accepts text file of developers and compiles into Java class file. It is a form of output generated by the compiler which has Java byte code. In Java, the main compiler is Javac.
• Debuggers – It is a Java program that allows Java developers to test and debug Java programs.
• JavaDoc – JavaDoc is comprehensive documentation prepared by Sun Microsystems for Java. It can be used for generating API documentation in an HTML file from the source code.

JRE

JRE contains an instance of JVM with it, development tools, and library classes. Once the Java code is written and compiled, the compiler creates a class file having byte code.

The key components of JRE include:

• Class loaders – The class loader loads different classes that are essential for executing Java code. JVM uses three class loaders namely the bootstrap class loader, extensions class loader, and system class loader.
• Byte code verifier – It verifies the byte code so the code does not interrupt the interpreter.
• Interpreter – When the classes are loaded and the code is verified, the interpreter reads the code line by line.
• Runtime – Runtime system is used primarily in programming to define the timeframe in which a specific program is running.
• Hardware – Once Java native code is compiled, it runs on a particular hardware platform.

So, this is how the Java program runs in JRE.

JVM

Here are the key components of JVM

• Class loader – It is a subsystem for loading class files. Its three main functions include Loading, Linking, and Initialization.
• JVM method area – This stores structure of class like the code for Java methods, metadata, and the continuous runtime pool.
• Heap – Heap stores all the objects, arrays, and instance variables. This memory is shared with several threads.
• JVM language stacks – This store local variables and partial results. Every thread has its own JVM language stack that is created as soon as the thread is created. When a method is invoked a new frame is created and removed when the method invocation process is completed.
• PC registers – The address of the JVM machine instruction which is currently executing is stored in PC registers. Each thread has its own PC register in Java
• Native Method Stacks – This store the instruction of native code relies on the native library. It either allocates memory on native heaps or utilizes any stack type.
• Execution Engine – Execution engine is used for testing software, hardware, or the complete system. No information about the tested product is carried by the test execution engine.
• Native Method interface – It is a programming framework that allows Java code that is running in a JVM to call native applications and libraries.
• Native Method libraries – It is a group of Native Libraries like C, C++ which are required by the Execution Engine.

So, these are the main differences between JDK vs JRE vs JVM. If you want to know more about Java Development Kit, Java Runtime Environment, or Java Virtual Machine, you can simply research online or contact us to know more in detail.

Summing Up…

For your better understanding, we, as a Java development company, have compared JDK vs JRE vs JVM side by side. Let’s have a look!

JDK	JRE	JVM
JDK stands for Java Development Kit.	JRE is an acronym of Java Runtime Environment.	JVM is an abbreviation of Java Virtual Machine.
JDK is a software development kit used for Java application development.	JRE is a software bundle that contains Java class libraries with key components to execute Java code.	It runs Java byte code and contains an environment for executing it.
It is platform-dependent.	It is platform-dependent.	It is platform-independent.
It has a set of tools for developing, debugging, and monitoring Java code.	It has class libraries and other supporting files that are needed by the JVM to run the program.	It does not come with software development tools.
It is the superset of JRE.	It is the subset of JDK.	It is a subset of JRE.
Using JDK, Java developers can create Java programs that can be executed and run by the JRE and JVM.	It is the part of Java that forms the JVM.	JVM is the Java platform component that runs source code.
JDK has the installer.	JRE only provides an environment for source code execution.	JVM is bundled in JDK as well as JRE.

If you’re looking to hire Java developers in India, you may get in touch with us, discuss your requirements, and get started.

Being a leading Java development company, we specialize in building robust Java applications for global clients from a diverse range of industries. For further queries or information about our services, we are always here to help you out.

FAQs

Q.1. What applications are written in Java?

Ans. Here are some of the examples of applications written in Java:

• NASA World Wind
• Google and Android OS use Java for many of their products.
• Netflix
• Amazon
• LinkedIn
• Uber
• Spotify
• Minecraft

Q.2. Where is Java used today?

Ans. Java is one of the most popular and widely used programming languages that is used as the server-side language for numerous backend development projects like those involving big data and Android app development. Java is mostly used for desktop and mobile computing, game development, and numerical computing.

Q.3. How do I hire Java developers in India?

Ans. If you’re looking to hire Java developers in India, there are certain things you need to consider to hire the best one for your Java project. They include:

• Years of experience and expertise of the developer
• Work portfolio
• References
• Client Reviews and Ratings
• Technical skills
• Communication skills
• Soft skills
• Post-development support
• Development time and cost
• Safety and Security

If you’re planning to hire Java developers in India, you should consider hiring from a well-established Java development company. Java India is a leading Java development company that you can trust for Java development services.