JDK vs. JRE: When Should You Use Each?

JDK vs. JRE: Understanding Their Roles and Usage

Question:

What is the distinction between the Java Development Kit (JDK) and the Java Runtime Environment (JRE), and when should one use one or the other?

Answer:

JRE (Java Runtime Environment)

The JRE contains all the essential components for executing compiled Java applications, including:

• Java Virtual Machine (JVM)
• Java Class Library
• java command
• Other necessary infrastructure

However, it lacks the capability to create new Java programs.

JDK (Java Development Kit)

The JDK encompasses everything in the JRE, along with additional features crucial for Java programming:

• Compiler (javac)
• Tools (e.g., javadoc, jdb)

As a full-fledged SDK, the JDK allows for the creation, compilation, and execution of Java applications.

Choosing between JDK and JRE

Generally, if your sole purpose is to run Java applications, installing the JRE is sufficient. However, if you intend to engage in Java development, the JDK is the preferred choice.

Even in situations where you may not plan to directly develop Java programs, the JDK may be necessary. For instance, when deploying a web application with JSP, you are essentially executing Java programs within the application server. The application server compiles JSP into Java servlets, which requires the JDK for this process.

Ultimately, the choice between JDK and JRE depends on your specific requirements. The former is tailored for Java development, while the latter focuses on running Java applications.

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