JVM, JRE, JDK에 대한 이해

Understanding of JVM, JRE, JDK in JAVA

Java is one of the most popular programming languages in the world. It is used to develop a wide range of applications, from web applications to mobile apps. However, to understand how Java works, it is important to understand the three main components of the Java platform: JVM, JRE, and JDK.

Summary

In this article, we will explore the three main components of the Java platform: JVM, JRE, and JDK. We will explain what each component does and how they work together to run Java applications. We will also provide code examples to help you understand how these components work in practice.

What is JVM?

JVM stands for Java Virtual Machine. It is an abstract machine that provides a runtime environment for Java applications. The JVM is responsible for interpreting Java bytecode and executing it on the underlying hardware.

The JVM is designed to be platform-independent, which means that Java applications can run on any platform that has a JVM installed. This is one of the reasons why Java is so popular for developing cross-platform applications.

What is JRE?

JRE stands for Java Runtime Environment. It is a software package that includes the JVM, libraries, and other components that are required to run Java applications. The JRE does not include development tools, such as compilers and debuggers.

When you install Java on your computer, you are actually installing the JRE. This allows you to run Java applications on your computer without having to install a separate JVM.

What is JDK?

JDK stands for Java Development Kit. It is a software package that includes the JRE, development tools, and other components that are required to develop Java applications. The JDK includes a compiler, debugger, and other tools that are used to write, compile, and test Java code.

When you install the JDK on your computer, you get everything you need to develop Java applications. This includes the JRE, which allows you to run Java applications on your computer, as well as the development tools that are required to write and test Java code.

How do JVM, JRE, and JDK work together?

The JVM, JRE, and JDK work together to run Java applications. When you write Java code, you use the JDK to compile it into bytecode. The bytecode is then executed by the JVM, which interprets the code and executes it on the underlying hardware.

The JRE is used to run Java applications on your computer. When you install Java on your computer, you are actually installing the JRE. This allows you to run Java applications without having to install a separate JVM.

Code Example

Here is a simple Java program that demonstrates how the JVM, JRE, and JDK work together:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

To compile this program, you would use the JDK's javac command:

javac HelloWorld.java

This would generate a bytecode file called HelloWorld.class. To run the program, you would use the JRE's java command:

java HelloWorld

This would execute the program and output the following message:

Hello, World!

Conclusion

In conclusion, understanding the JVM, JRE, and JDK is essential for anyone who wants to develop Java applications. The JVM provides a runtime environment for Java applications, while the JRE includes the JVM and other components that are required to run Java applications. The JDK includes the JRE and development tools that are required to write, compile, and test Java code. By understanding how these components work together, you can develop and run Java applications with confidence.