leejunkim

JVM, JRE, JDK & the Compilation Process

2 min read

WTH is JVM, JRE, JDK?

  • diagram

Java Development Kit (JDK)

a software development kit that provides a set of tools and libraries for developing Java applications

  • essential for developers who want to write, compile, and run Java code
  • you will need to download this when developing Java applications

Java Runtime Environment (JRE)

A package that provides the libraries JVM needs to run Java applications

  • Program that executes compiled Java bytecodes
  • Does not include development tools, making it suitable for users who only need to run Java programs without developing them
    • Install the JRE when you only need to run Java applications but not develop them
  • subset of the JDK

Java Virtual Machine (JVM)

The compilation process

  1. Developer writes the .java files in Java (ex. MyProgram.java)
  2. Compilation
    • The Java Compiler (a program named javac ) reads your .java source file
    • It translates your code into Java Bytecode (Saved in a file with extension .class)
      • A set of instructions specifically designed to be read by Java Virtual Machine (JVM)
      • It’s not tied to any OS or hardware, and this is the core of Java’s “write once, run anywhere” principle
      • The same .class file can run on any computer that has a compatible JRE
    • Ex. MyProgram.java becomes MyProgram.class
  3. Running the program
    • To run the .class file you need the JRE

Graph View

Backlinks