Java Interview Questions

JDK (Java Development Kit)

• Purpose: The JDK is a software development kit used to develop Java applications and applets.
• Components: It includes development tools like the compiler (javac), a runtime environment (JRE), and other utilities for development.
• Usage: Required by developers to write and compile Java programs.

JRE (Java Runtime Environment)

• Purpose: The JRE provides the libraries, Java Virtual Machine (JVM), and other components to run applications written in Java.
• Components: It includes the JVM, core libraries, and other supporting files but does not include development tools like compilers and debuggers.
• Usage: Used by end-users to run Java applications.

JVM (Java Virtual Machine)

• Purpose: The JVM is a specification that provides a runtime environment in which Java bytecode can be executed. It abstracts the underlying platform details and provides a consistent runtime environment.
• Components: It includes a class loader, memory area, execution engine, and other components needed to run Java bytecode.
• Usage: It is a part of the JRE and is responsible for executing the Java application.

Summary

• JDK: For developing Java applications (includes JRE + development tools).
• JRE: For running Java applications (includes JVM + libraries).
• JVM: For executing Java bytecode (part of JRE).