How To Set Java And Maven Path In Environment Variables

This is an extension posts outlining setting upwards & getting started with Java & Maven.

Q1. What is the difference betwixt JDK & JRE?
A1. JDK: You can download a re-create of the Java Development Kit (JDK) for your operating system similar Windows 64 bit, Mac Bone X, Linux X64, Solaris X64, etc.

JRE: Coffee Runtime Environment is an implementation of the JVM. The JDK typically includes the Java Runtime Environs (JRE) which contains the virtual car and other dependencies to run Java applications. If you just only want to run Java applications without any evolution work, then you can download the JRE for your operating organisation similar Windows 64 bit, Mac Os Ten, Linux X84, Solaris X64, etc.

Q2. How does Coffee's WORA (i.e. Due westrite Once Run Anywhere) work?
A2. Yous can develop a Coffee application as a "xxx.jar" file in Windows 64 bit OS, which essentially contains "*.class" files compiled with java.exe shipped with the JDK for "Windows 64". This "xxx.jar" file can be deployed & run in a Linux box running "JRE for Linux X64". The "JRE for Linux X64" will read the "*.class" files in byte code created with "JDK Windows 64 bit", and convert the byte code to Linux auto code so that the Linux OS volition sympathize.

Q3. What are environment variables?
A3. An environment variable defines some aspect of a user's or a plan'due south environment. After you lot have installed the JDK or JRE in Windows, you must set the JAVA_HOME or JRE_HOME environment variables to point to the installation directory. Same applies for other applications like Maven. These variables are then used to ready the "PATH" variable so that when you type "coffee" or "mvn" in a DOS control-line, the application can be constitute.

In a Windows platform, you can write a batch file to set your environment variables equally shown beneath:

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@ echo off

REM This is sample to set upwards your Java and Maven environment variables

Set TOOLS_HOME=C : \ tools

Ready USERPROFILE=% TOOLS_HOME % \ home

Set JAVA_HOME=% TOOLS_HOME % \ java \ jdk1 . half-dozen.0_45

Set up M3_HOME=% TOOLS_HOME % \ maven \ apache-maven-3.1.0

Set up MAVEN_OPTS=-Xmx512m -Duser . domicile=% USERPROFILE %

Set up PATH=% PATH % ; % M3_HOME % \ bin ; % JAVA_HOME % \ bin

echo ******** Coffee Toolkit setup ****************

echo USERPROFILE = % USERPROFILE %

repeat JAVA_HOME = % JAVA_HOME %

echo M3_HOME = % M3_HOME %

echo PATH = % PATH %

echo ********************************************

Q4. How exercise you list the environment variables on DOS command prompt?
A4 By typing the "set" command.

Q5. How practice yous list the environment variables on Unix command prompt?
A5 Past typing the "env" control.

Q6. How exercise echo a particular surroundings variable?
A6. Typing the "echo %M3_HOME%" command displays "M3_HOME" variable. In Unix utilize "echo $M3_HOME".

Q7. How practice you find out in which folder an awarding similar Java or Maven is installed?
A7. In DOS, utilise "where" control equally in "where java", "where mvn", etc. In Unix, use "which" control as in "which java", "which mvn", etc.

Q8. How will you lot set your surround variables on an account or System level on Windows eight or later on?
A8. On Windows 8, search for "Edit environment variables".

Then, you can set information technology via the pop up GUI

Q9. Maven uses a settings.xml file for its configuration. How do y'all find out which settings.xml file is existence used by Maven?
A9. With the debug option mvn -Ten command.

[ INFO ] Error stacktraces are turned on .

[ DEBUG ] Reading global settings from C : \ TOOLS \ maven \ apache-maven-3.1.0 \ bin \ . . \ conf \ settings . xml

[ DEBUG ] Reading user settings from C : \ Users \ akumaras \ . m2 \ settings . xml

[ DEBUG ] Using local repository at c : \ tools \ dwelling \ . m2 \ repository

[ DEBUG ] Using director EnhancedLocalRepositoryManager with priority x.0 for c : \ tools \ home \ . m2 \ repository

You can get both the settings.xml file and the repository location "c:\tools\home\.m2\repository" where the artefacts will be downloaded to.

Maven uses the user.home property that can be set via MAVEN_OPTS environment property to set JVM heap memory.

SET MAVEN_OPTS=-Xmx512m -Duser . home=% USERPROFILE %

Q10. How practise you know that your Coffee and Maven are fix correctly?
A10. Typing "java" or "mvn" on a command prompt should recognize the command.

Q11. How does Maven know where to download the library jar files from? In other words, where do you specify the "Maven primal repository URL"?
A11. Via the global "settings.xml file or projection specific "pom.xml" file.

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< settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"

xmlns : xsi="http://www.w3.org/2001/XMLSchema-case"

xsi : schemaLocation="http://maven.apache.org/SETTINGS/1.0.0

http://maven.apache.org/xsd/settings-1.0.0.xsd" >

. . . .

< profiles >

< profile >

< id > securecentral </id >

< !--Override the repository ( and pluginRepository ) "central" from the

Maven Super POM -->

< repositories >

< repository >

< id > central </id >

< url > http : //repo1.maven.org/maven2</url>

< releases >

< enabled > true </enabled >

</releases >

</repository >

</repositories >

< pluginRepositories >

< pluginRepository >

< id > central </id >

< url > http : //repo1.maven.org/maven2</url>

< releases >

< enabled > true </enabled >

</releases >

</pluginRepository >

</pluginRepositories >

</profile >

</profiles >

. . .

</settings >

OR via the project specific "pom.xml" file

< project xmlns="http://maven.apache.org/POM/iv.0.0" xmlns : xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi : schemaLocation="http://maven.apache.org/POM/four.0.0 http://maven.apache.org/maven-v4_0_0.xsd" >

. . .

< repositories >

< repository >

< id > cloudera </id >

< url > https : //repository.cloudera.com/artifactory/cloudera-repos/</url>

</repository >

</repositories >

. . .

</project >

Q12. If I already accept the jar file, tin can I manually install into my local Maven repository ?
A12. Yep, use the following command

mvn install : install-file \

-DgroupId=org . springframework \

-DartifactId=spring-cadre \

-Dpackaging=jar \

-Dversion=3.ane.0.RELEASE \

-Dfile=jta-1.0.1B.jar \

-DgeneratePom=truthful

Q13. How exercise y'all search for artifacts on the central repository?
A13. Go to cardinal repository website http://search.maven.org/ and search. Prefix with k: for groupid, a: for artifactid, and v: for version number.