JDK vs JRE
JDK (Java Development Kit):
The JDK, or Java Development Kit, is a software development kit used to develop Java applications. It contains tools needed for Java programming, including a compiler, debugger, and other utilities. Here are its key components:
Compiler: The JDK includes the Java compiler (javac), which translates Java source code into bytecode, an intermediate language that can be executed by the Java Virtual Machine (JVM).
JVM (Java Virtual Machine): The JDK contains the JVM, which is responsible for executing Java bytecode. Different implementations of the JVM exist for various operating systems.
Java API (Application Programming Interface): The JDK provides a rich set of pre-built classes and libraries, collectively known as the Java API, that developers can use to build applications.
Development Tools: JDK includes various development tools like JavaDoc (for generating documentation), Java Debugger, and Java Archive (JAR) tools for packaging applications.
Sample Code and Demos: JDK often includes sample code and demos to help developers understand how to use Java features.
Developers use the JDK to write, compile, and debug Java applications. It's a complete package for Java development, suitable for developers creating Java software.
JRE (Java Runtime Environment):
The JRE, or Java Runtime Environment, is an environment in which Java applications run. It includes everything needed to run a Java program, but it lacks the development tools found in the JDK. Here's what the JRE includes:
JVM (Java Virtual Machine): Similar to the JDK, the JRE includes the JVM, allowing Java bytecode to be executed on the host system.
Java API: The JRE contains the Java API libraries, enabling Java applications to access standard functionalities like input/output operations, networking, and data structures.
Java Plugins: JRE includes browser plugins that enable Java applets to run in web browsers.
Java Web Start: JRE supports Java Web Start, which allows Java applications to be launched from a web browser.
No Development Tools: Unlike the JDK, the JRE does not include development tools such as compilers and debuggers.
In summary, while the JDK is intended for Java development, including both development and runtime components, the JRE is solely for running Java applications and lacks the development tools necessary for creating new Java programs. Developers need the JDK for creating Java applications, while end-users who want to run Java applications only require the JRE.
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