What is the difference between JVM, JDK and JRE

The editor of Downcodes will take you to understand three important concepts often encountered in Java development: JVM, JRE and JDK. They are closely related, but each performs its own duties. Understanding them is crucial for Java programmers. This article will explain the differences and connections between the three in a simple and easy-to-understand manner to help you better master the Java development environment.

When discussing the Java programming language and its environment, we often encounter the three words JVM, JDK, and JRE. Each word has its own specific definition and role. Let’s take a closer look at the differences between these three. The Java Virtual Machine (JVM) is part of the Java platform and is responsible for executing Java bytecode. The Java Runtime Environment (JRE) is the environment required to run Java programs. The Java Development Kit (JDK) is a development environment for Java.

1. JVM (Java Virtual Machine)

The Java Virtual Machine (JVM) is part of the Java platform and is responsible for executing Java bytecode. JVM is the core of Java, which enables Java to have the characteristics of "write once, run anywhere". When running a Java program, the JVM is responsible for converting the bytecode into machine instructions for specific platforms (such as Windows, Linux, etc.).

2. JRE (Java Runtime Environment)

The Java Runtime Environment (JRE) is the environment required to run Java programs, including the JVM, Java class library (Java API) and other files required to run Java applications. JRE can be regarded as the implementation of JVM, which provides the environment required for Java programs to run.

3. JDK (Java Development Kit)

Java Development Kit (JDK) is a Java development environment, which includes JRE and a series of development tools, such as compiler (javac), Java application packaging tool (jar), etc. JDK is a collection of all tools and running environments needed to develop Java programs. It is an essential tool for Java program developers.

In general, the relationship between JVM, JRE and JDK can be understood this way: JDK is used to develop Java applications, JRE provides an environment for running Java programs, and JVM is the core of realizing Java's cross-platform features.

Further reading

Java Programming Language: Java is a widely used computer programming language designed for developing object-oriented applications in a distributed environment. Java platform: The Java platform is the running environment of Java, which consists of JVM and Java class library. Java class library: Java class library is a set of precompiled classes provided by Java, which provides developers with various basic functions. Java cross-platform features: Java's cross-platform features mean that Java applications can run on different operating systems and hardware architectures, which is achieved through the JVM. Java development tools: Java development tools are tools used to develop Java applications, including compilers, debuggers, document generators, etc. Java version: With the development of technology, Java is constantly updated and improved, and each version adds some new features and functions. Understanding the various versions of Java and their differences can help developers make better use of Java's features.

I hope the explanation by the editor of Downcodes can help you better understand JVM, JRE and JDK. If you have any questions, please feel free to leave a message!