💻3: JVM, JRE, JDK – Unlock Java components

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ComparisonJDKJREJVM
DefinitionA software development kit used to develop Java applicationsA software package that contains what is required to run a Java applicationAn abstract computing machine that enables a computer to run a Java program
IncludesCompiler (javac), interpreter (java), libraries, documentation, other toolsInterpreter (java), libraries, Java Plug-in (for running Java applets in a web browser)JIT, Libraries and class files
PurposeTo develop Java applicationsTo run Java applicationsTo execute Java bytecode
InstallationRequired to develop Java applicationsRequired to run Java applicationsComes bundled with JDK or JRE

💡(1) J.V.M (Java Virtual Machine)-

J.v.m = j.i.t(just-in-time compiler)+cache

💡-> J.v.m Doesn’t exists physically, It just resides in RAM

💡-> J.v.m provides specifications to execute java byte-code.

💡-> J.v.m is platform dependent and easily available for many platforms(OS)

Note – We can’t refer any particular file as windows, it’s a group of specifications which provides environment to run software, similarly JVM only runs Java compiled codes(bytecodes).

*JVM internal architecture*-

💡(2)JRE (Java Runtime Environment)-

💡–> implementation of JVM.

💡–> physically exists.

JRE = JVM + Set of libraries (i.e. jar) + Other Files

Note – To run java program we only need to install JRE, to develop java program we need to install JDK.

💡(3)JDK (Java Development Kit)-

💡–> physically exists.

💡 JDK = JRE + Development tools(i.e. javac, java etc)

Interview Questions —

  • How to install JVM?
  • Is Windows JVM different than Linux/Mac JVM?
  • Does installing JDK automatically installs JRE and JVM ?

7 comments

  1. Can you be more specific about the content of your article? After reading it, I still have some doubts. Hope you can help me.

  2. If you would like to increase your familiarity just keep visiting this website and be updated with the hottest
    news posted here.

  3. you can consider jvm as a computer for which machinre language is bytecode .
    And jre builds this virtiual computer (i.e jvm) on your machine(p.c) so it can run program .

  4. Sir can you plz elaborate some useful tools(Java,javaw,javap etc.) of jdk

    • yes, of course…
      Basic Tools
      These tools are the foundation of the JDK. They are the tools you use to create and build applications.
      1-javac The compiler for the Java programming language.
      2-java The launcher for Java applications.
      3-javadoc API documentation generator.
      4-apt Annotation processing tool.
      5-jar Create and manage Java Archive (JAR) files.
      6-jdb The Java Debugger.
      7-javap Class file disassembler

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