Installing maven problems - java

I have just installed Maven. I execute in a CMD console mvn -version, it works.
C:\>cd apache-maven-3.3.3
C:\apache-maven-3.3.3>mvn -version
Apache Maven 3.3.3 (7994120775791599e205a5524ec3e0dfe41d4a06; 2015-04-22T13:57:3
7+02:00)
Maven home: C:\apache-maven-3.3.3
Java version: 1.8.0_25, vendor: Oracle Corporation
Java home: C:\Program Files (x86)\Java\jre1.8.0_25
Default locale: es_ES, platform encoding: Cp1252
OS name: "windows 8", version: "6.2", arch: "x86", family: "dos"
When I try to execute command c:\mvn -version I receive a list with the possible commands of java.
What can be the reason for that?

I believe that you have not set the PATH variable in your windows system.
Navigate to Advanced System Settings -> Environment Variables -> System Variables
Copy "C:{path_to_maven}\bin" and append it to your 'Path'
environment variable.
And Also it is recommended that you set the
M2_HOME
in the User Variables Section to "C:{path_to_maven}\" so that you do not run into troubles in the future
If you need more details, go to the official page of maven by clicking on this link.

Add M2_HOME variable in the Windows environment, and point it to your Maven folder. Update PATH variable, append Maven bin folder: %M2_HOME%\bin, so that you can run the Maven’s command everywhere.

Related

Error "the JAVA_HOME environment variable is not defined correctly" on running "mvn clean javadoc:jar package"

When I try to execute the command
mvn clean javadoc:jar package
it shows
the JAVA_HOME environment variable is not defined correctly. This environment variable is needed to run this program.
NB: JAVA_HOME should point to a JDK, not a JRE.
I checked out the already asked question Unable to find javadoc command - maven and the solution I tried above were taken from this solution only. I am new to Ubuntu. How can I fix this?
Whereas when I run echo $JAVA_HOME it prints:
/usr/lib/jvm/java-11-openjdk-amd64
I also tried setting the JAVA_HOME to:
/etc/launchd.conf/java-11-openjdk-amd64
/usr/libexec/java-11-openjdk-amd64
/usr/libexec/java-11-openjdk-amd64/
When I run mvn -v, it prints:
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 11.0.10, vendor: Ubuntu, runtime: /usr/lib/jvm/java-11-openjdk-amd64
Default locale: en_IN, platform encoding: UTF-8
OS name: "linux", version: "5.8.0-45-generic", arch: "amd64", family: "unix"
And when I run echo $JAVA_HOME it prints:
/usr/lib/jvm/java-11-openjdk-amd64
Hmm..., probably the file doesn’t exist for running javadoc. Does the file /usr/lib/jvm/java-11-openjdk-amd64/bin/javadoc exist?
Please try:
sudo apt install openjdk-11-jdk
I would remove the above listed packages with pattern openjdk-11-.* (see this question) and install Java like this.
On my Mac (big Sur) I was getting the same problem. After reading this article ; this command worked for my enviroment:
export JAVA_HOME=$(/usr/libexec/java_home)

Setting up Microsoft Code for java with WSL

I try to set the visual code settings for .csvode settings.json for wsl to the path where the wsl resides with the home folder. But I keep getting error that it does not point to a jdk. I have tried pointing to the local installation on windows as well as the place where the jdk resides on the wsl. None of which is working.
$ mvn -version
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 11.0.8, vendor: Ubuntu, runtime: /usr/lib/jvm/java-11-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "4.4.0-18362-microsoft", arch: "amd64", family: "unix"
Tested and failed settings of the wsl settings:
{
"java.home": "C:\\Java\\java-11-openjdk-11.0.8.10"
}
and
{
"java.home": "/usr/lib/jvm/java-11-openjdk-amd64"
}
As well as variants where I add or remove slashes as well as bin folder.
Press Ctrl+Shift+P to open Command Platte and choose Java: Configure Java Runtime:
Turn to Java Tooling Runtime, JDK for Language Server will show all installed and eligible JDK for java extension, which is jdk11 or recent version. Choose the one that you've installed:
Then reload VS Code to make change effective.

Error: Could not find or load main class $MAVEN_HOME

while running maven clean I am getting the following error :
Error: Could not find or load main class $MAVEN_HOME
while doing mvn -version I got :
Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-10T22:11:4
7+05:30)
**Maven home: D:\mavenSecurity\apache-maven-3.3.9\bin\..**
Java version: 1.7.0_79, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.7.0_79\jre
Default locale: en_IN, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "x86", family: "windows"
I have set MAVEN_HOME = D:\mavenSecurity\apache-maven-3.3.9 in user variable in environment setting
Path in system variable in environment setting : D:\mavenSecurity\apache-maven-3.3.9\bin
Since I am getting other error previously so I have done the following also as mentioned in this post:
Eclipse error setting up Maven project for class exercise: Check $M2_HOME environment variable and mvn script match
-Dmaven.multiModuleProjectDirectory=$MAVEN_HOME
I have consulted other links but still I am getting the error while running MAVEN CLEAN in eclipse juno
This worked for me with the 3.3.9 version. The only difference is :
1) Add both M2_HOME and MAVEN_HOME variables in the Windows environment, and point it to your Maven folder (Note: I have added it to system variables)
2) Update PATH variable, append Maven bin folder – %M2_HOME%\bin, so that you can run the Maven’s command everywhere
Post output of mvn –version again if you face the issue. Also try running mvn clean from the command line and post the results.
configuring Maven on Eclipse. you have to tell eclipse where Maven has been installed so that it can use the Maven installation to build our projects.
Win 7 64 . Here is how i did my config.

How does maven know JAVA_HOME set as an environment variable inUbuntu

When I type mvn --version in ubuntu from the terminal(ubuntu),I get the below output.
Warning: JAVA_HOME environment variable is not set.
Apache Maven 3.0.5
Maven home: /usr/share/maven
Java version: 1.7.0_79, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-7-openjdk-amd64/jre
Default locale: en_IN, platform encoding: UTF-8
OS name: "linux", version: "3.13.0-32-generic", arch: "amd64", family: "unix"
When I did not set any JAVA_HOME environment variable , how is maven getting the java home installed path.Is it trying to find this path from the /usr/bin/java command which is installed in my system and if so why is it taking the path till jre.
P.S : Also I could not find any java path in any maven config.
Thanks.
As showed in the CLIReportingUtils.java (the maven class that retrieves the Java Home), the value comes from the following call :
System.getProperty( "java.home", "<unknown java home>" )
The java.home is for the JRE unlike the JAVA_HOME which is for the JDK.
So Maven is displaying the JRE home.
I would say there is a difference between JAVA_HOME environment variable and the output Java home: /usr/lib/jvm/java-7-openjdk-amd64/jre.
The latter is just the output of the installation directory see here.
So maven will run Java in background and java knows where its installed.
I think,I understand it now.In the maven script i.e (usr/share/maven/bin/mvn) they are trying to find the java installed using a variety of options.
So at one place they are doing the below
JAVACMD="`which java`"
And now in my system "which java" points to the below
java -> /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java
Hope this is how its getting the java path.

${java.home} changes when running Maven on a OS X

This appears to be a problem I do not see on linux or Windows machines. I have my environment setup with a JAVA_HOME derived from /usr/libexec/java_home. This is in my .bashrc file:
export JAVA_HOME=$(/usr/libexec/java_home -version 1.7)
which results in:
~/dev/Endeavor/endeavor-sdk$ echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.7.0_17.jdk/Contents/Home
However when I run Maven on my project, I get an error from the native2ascii plugin:
[ERROR] Failed to execute goal org.codehaus.mojo:native2ascii-maven-plugin:1.0-alpha-2-SNAPSHOT:native2ascii (default) on project dataAccessServices: Error starting Sun's native2ascii: -> [Help 1]
My investigation points to that I am using a JRE instead of a JDK. That's odd since I am clearly pointing to the JDK in my JAVA_HOME variable. However, here is the output of mvn -version:
~/dev/Endeavor/endeavor-sdk$ mvn -version
Apache Maven 3.0.4 (r1232337; 2012-01-17 03:44:56-0500)
Maven home: /usr/share/maven
Java version: 1.7.0_17, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.7.0_17.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.7.5", arch: "x86_64", family: "mac"
Notice the "Java home:" line indicates that the ${java.home} variable has been moved to the JRE instead of the JDK that the JAVA_HOME environment variable points to.
I have tried setting the JAVA_HOME in numerous places but I can't seem to find a way to get maven to use the JDK as the home and not the JRE.
UPDATE:
I found this that appears to indicate that this is expected behavior: Java_home in Maven
But that does not explain why the native2ascii plugin cannot find the JDK tool it needs.
I have removed the use of native2ascii since it was largely unnecessary. So, I am avoiding the problem at this point. However, if anyone has an idea as to why this behaves differently on different systems, please let me know.
Have you tried running mvm help:system that should print all environment variable values that are relevant to maven?
There has been lots of discussions on this matter and here Java_home in Maven you can find a real good answer.
In a nutshell: your configuration it's just right, it is just a matter of semantics. You can read further here: http://javahowto.blogspot.com/2006/05/javahome-vs-javahome.html

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