What is the difference between JDK and JRE?
Understanding the roles of JDK (Java Development Kit) and JRE (Java Runtime Environment) is key for Java developers. Learn how they differ in purpose—one is for development, the other for running Java applications.
The difference between JDK (Java Development Kit) and JRE (Java Runtime Environment) is a common point of confusion for beginners in Java, but it's actually quite simple once you break it down.
- JRE is designed for running Java programs. It includes the Java Virtual Machine (JVM), core libraries, and other components necessary to execute Java applications. However, it does not include tools for developing Java applications (like javac, the Java compiler).
- JDK, on the other hand, is meant for developing Java applications. It includes everything the JRE has, plus a full suite of development tools—like the compiler (javac), debugger (jdb), and other utilities.
So if you’re only running Java programs, you just need the JRE. But if you want to write, compile, and debug Java code, you must install the JDK.
- Here’s a quick comparison:
- ✅ JDK = JRE + development tools
- ✅ JRE = JVM + core libraries (runtime only)
- Use JDK if you’re writing or compiling Java code.
- Use JRE if you're running Java applications but not developing them.