Tag Archives: JRE

JDK, JRE, JIT,SDK, JVM Introduction

JDK (Java  Development Kit)

JDK (Java Development Kit) is a superset of JRE (Java Runtime Environment), it contains everything that JRE has along with development tools such as compiler, debugger, etc.

JDK Java development Kit
Java Development Kit

See Also: Java: Program Execution

JRE (Java Runtime Environment)

JRE (Java Runtime Environment) provides the environment in which the JVM (Java Virtual Machine) runs. JRE contains JVM, class libraries, and other files excluding development tools such as compiler and debugger.

It means, you can run the code in JRE but you can’t develop and compile the code in JRE.

JDK and JRE Formulae

JVM (Java Virtual Machine)

JVM (Java Virtual Machine) runs the program by using class, libraries, and files provided by JRE. JVM able to run a program written in Java and other languages also that are compiled to Java byte code. For Example Jython, Jruby, Closure, Apache, Groovy, Kotlin, etc.

JVM Architecture

Now discussed terminology used for JVM.

Class Loader

The class loader reads the .class file and saves the byte code in the method area.

Method Area

Method area holds class level information of .class file. JVM jave only one method area which is shared among all the classes.


Heap is a JVM memory part where objects are allocated. JVM creates an object for each .class Class file.


The stack is  JVM memory part but unlike Heap, it is used for storing temporary variables i.e method parameters.

PC Registers

PC Registers use to keeps the track of which instruction has been executed and which one is going to be executed. Because instructions are executed by threads, each thread has a separate PC register.

JIT Compiler

The JIT also called a Just-In-Time compiler. It used when a method is called. The JIT compiles the bytecode of that called method into native machine code. When a method has been compiled in native machine code, the JVM calls the compiled code of that method directly instead of interpreting it.

Native Method Stack

A native method used to access the runtime data areas of the virtual machine.

Native Method interface

It enables java code to call or be called by native applications wiritten in C or C++. Native applications are programs in low-level language that is specific to the hardware and OS of a system.

Garbage collection

Garbage Collection use for automatic memory management by JVM. It destroys unreferenced objects from Heap so that allocates more memory for new objects.

JDK Architecture & API’s Details

In this figure, you will get an idea of how these libraries and API’s are distributed on different levels.

JDK APIs Architecture

Difference between API and Methods

API (Application Programming Interface) interfaces that the rest of the world sees and can use. A Method can be part of the public interface or not. But an API executes a set of methods.

In java, APIs provide through the interface which is really a set of public methods. An API has contract like tells about method signatures and return type.

For Example List API’s provide different method signature and expected result as return type so that you can use according to your convenience.

Difference between JDK and SDK

JDK(Java Development Kit) is an extended subset of a SDK (Software Development Kit).

  • JDK includes tools for developing, debugging and monitoring of Java Program. It mainly responsible for the writing and running of Java programs.
  • SDK is composed of extra software related to a Web application or mobile application etc. such as Application Server, Documentation, Debuggers, Code Samples, Tutorials, GlassFish server, MySQL and IDE Netbeans.

Now, Oracle strongly suggests using the term JDK to refer to the Java SE Development Kit. The Java EE SDK is now available with or without the JDK, by which they specifically mean the Java SE 7 JDK.

See Also: Java Versions History



[Solved] Maven: No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK

This maven exception occurs  when your Window/Unix environment variable for JAVA_HOME and PATH are pointing to JRE instead of JDK. That’s why maven will not compile code and throw below exception.


[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Building SpringBootApp 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-install-plugin/2.5.2/maven-install-plugin-2.5.2.pom
[INFO] Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-install-plugin/2.5.2/maven-install-plugin-2.5.2.pom (7 KB at 2.3 KB/sec)
[INFO] Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-plugins/25/maven-plugins-25.pom
[INFO] Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-plugins/25/maven-plugins-25.pom (10 KB at 10.2 KB/sec)
[INFO] --- maven-resources-plugin:3.0.1:resources (default-resources) @ SpringBootApp ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 0 resource
[INFO] Copying 0 resource
[INFO] --- maven-compiler-plugin:3.7.0:compile (default-compile) @ SpringBootApp ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to D:\Saurabh Gupta\facingIssuesOnIT\SpringBootApp\target\classes
[INFO] -------------------------------------------------------------
[INFO] -------------------------------------------------------------
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5.342 s
[INFO] Finished at: 2018-05-28T15:59:31+05:30
[INFO] Final Memory: 20M/209M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile (default-compile) on project SpringBootApp: Compilation failure
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
[ERROR] -> [Help 1]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException


To resolve this issue you can follow below steps by solving command prompt or Eclipse.

Command Prompt

How to Configure Maven in Window and Linux?


  • Right click on project -> Select Properties
  • Select Java Build Path-> Libraries Tab -> Click on Add Library
  • Refer below link for reference.

Eclipse : How to set java path of JDK/JRE?

Eclipse : How to set java path of JDK/JRE?

To set path of JDK for your project in eclipse follow below steps:

  • Right click on your project -> select properties.
  • Click in Library tab
  • To remove or update JRE/JDK remove existing from list as below.


Eclipse ClassPath Setting 1
Eclipse : How to set JDK/JRE Path


  • Click on add Library and select option as “JRE System Library” and click on Next button.


Eclipse ClassPath Setting 2
Eclipse : How to set JDK/JRE Path


  • If you need to use existing JRE/JDK you can select from installed JRE or if need to add new one click on Add button.
  • You will get popup of JRE definition. click on Directory option and select JAVA (JRE/JDK) version home directory as in below screen shot
  • Click on Finish button.


Eclipse ClassPath Setting 3
Eclipse : How to set JDK/JRE Path


  • Select one Installed JRE which want to use on your project.
  • Click on “Apply and Close” button.


Eclipse ClassPath Setting 4
Eclipse : How to set JDK/JRE Path


  • Finally selected JRE/JDK added to your project.
  • Click on “Apply and Close” button.


Eclipse ClassPath Setting 5
Eclipse : How to set JDK/JRE Path