Java is a very popular programming language among developers for creating a variety of applications ranging from desktop software to web applications and mobile applications. When working with Java, programmers often come across some common terminologies like JDK, JRE, and JVM, all of which are important components of the Java ecosystem.
The Java Development Kit (JDK), the Java Runtime Environment (JRE), and the Java Virtual Machine (JVM) are three independent components of the Java ecosystem that are used to run Java applications, and all three of them serves a different purpose. Identifying and knowing the differences between these components is important for Java developers and also for those who are planning to start learning Java programming language. We will go over the difference between JDK JRE and JVM in this blog and will try to explain in simple words why each of these components is essential in the Java development process.
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 | JRE | 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. |
Conclusion
In conclusion, Java has three main components: the JDK, JRE, and JVM. The JDK has the development tools needed for creating Java applications, while the JRE provides a runtime environment for executing Java applications. The JVM is responsible for executing Java bytecode and converting it into machine code.
FAQs
Here are some frequently asked questions
Q1: Is the JRE required to run Java applications?
A: 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.
Q2: Is the JVM platform independent?
A: Yes, JVM is platform-independent, which means that we can run the same bytecode on any machine that has a compatible JVM installed in it.
Q3: Is the JDK platform independent?
A: The Java code written by the programmer using the JDK is platform-independent, but the JDK itself is platform-dependent. To develop java applications we need to download and install the appropriate version of the JDK that is compatible with our operating system.
Q4: What is the role of JavaFX?
A: JavaFX is a set of graphics and media APIs used for developing rich, cross-platform user interfaces for desktop, mobile, and web applications. JavaFX is included in the JDK starting from Java SE 7u6.