[java] Error: JAVA_HOME is not defined correctly executing maven

I installed java and set path to environment and when I execute echo $JAVA_HOME I get the following output:

/usr/lib/jvm/java-7-oracle/jre/bin/java

I Also installed apache-maven and changed environment file and now it looks like this:

JAVA_HOME="/usr/lib/jvm/java-7-oracle/jre/bin/java"
M2_HOME=/usr/local/apache-maven/apache-maven-3.0.5
M2=$M2_HOME/bin
MAVEN_OPTS="-Xms256m -Xmx512m"
PATH=$M2:$PATH

But when I execute mvn --version I get a warning:

Error: JAVA_HOME is not defined correctly.
  We cannot execute /usr/lib/jvm/java-7-oracle/jre/bin/java/bin/java

Can not find out why it repeats in the end /bin/java/bin/java

set as it is export JAVA_HOME=/usr/java/jdk1.8.0_31.and run with sudo it will execute..

Use these two commands (for Java 8):

sudo update-java-alternatives --set java-8-oracle
java -XshowSettings 2>&1 | grep -e 'java.home' | awk '{print "JAVA_HOME="$3}' | sed "s/\/jre//g" >> /etc/environment

You must take the whole directory where java is installed, in my case:

export JAVA_HOME=/usr/java/jdk1.8.0_31

You might get this error due to couple of reasons. To fix this quickly please follow below steps,

First find the java location. To get a list of your installed Java platforms, run the following command from the terminal:

$ sudo update-alternatives --config java

Now set JAVA_HOME and PATH,

$ export JAVA_HOME=<java_home>

$ export PATH=$JAVA_HOME/jre/bin:$PATH

Create the symlink

$ sudo ln -s <java_home>/jre <java_symlink_path>

When we take your case as a example :

$ sudo ln -s /usr/lib/jvm/java-7-oracle/jre /usr/lib/jvm/java-7-oracle/jre/bin/java

Above command will create the symlink location where the system is trying to find in your issue.

Finally do the

$ mvn --version

I had this same issue but with open jdk and none of the answers here helped. The trouble was that the mvn script was appending /bin/java at the end of JAVA home while trying to run java commands.

The solution for me was to manually edit the /usr/local/apache-maven/apache-maven-3.3.9/bin/mvn script (your own script might be installed differently; just run which mvn) and change

   if [ -z "$JAVACMD" ] ; then
  if [ -n "$JAVA_HOME"  ] ; then
    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
      # IBM's JDK on AIX uses strange locations for the executables
      JAVACMD="$JAVA_HOME/jre/sh/java"
    else
      JAVACMD="$JAVA_HOME/bin/java" 
    fi
  else
    JAVACMD="`which java`"
  fi
 fi

To

if [ -n "$JAVA_HOME"  ] ; then
    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
      # IBM's JDK on AIX uses strange locations for the executables
      JAVACMD="$JAVA_HOME/jre/sh/java"
    else 
      JAVACMD="$JAVA_HOME"
    fi
  else
    JAVACMD="`which java`"
  fi
fi

This solution work for me... just type export PATH=$JAVA_HOME/jre/bin:$PATH in the terminal then run mvn -version it will show the same error but with a log like this

which: no javac in (/jre/bin:/sbin:/bin:/usr/sbin:/usr/bin:/opt/puppetlabs/bin)
Warning: JAVA_HOME environment variable is not set.
Apache Maven 3.2.5 (12a6b3acb947671f09b81f49094c53f426d8cea1; 2014-12-14T22:59:23+05:30)
Maven home: /opt/apache-maven-3.2.5
Java version: 1.8.0_171, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el7_5.x86_64/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "3.10.0-693.el7.x86_64", arch: "amd64", family: "unix"

now copy the Java home path i.e. /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el7_5.x86_64/jre in my case.

now type,

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.171-8.b10.el7_5.x86_64/jre

and the error gets resolve. NOTE: paste your own path which is shown by your machine in mvn log at export JAVA_HOME.

JAVA_HOME should be /usr/lib/jvm/java-7-oracle/jre/.

We open a terminal and look for the location of java:

manuel@zonademanel:~ ? whereis java

java: /usr/bin/java /etc/java /usr/bin/X11/java /usr/share/java /usr/share/man/man1/java.1.gz

What we are looking for is /usr/bin/java continue on the command line to find the absolute path , as this is only a symbolic link.

manuel@zonademanel:~ ? ls -lah /usr/bin/java

lrwxrwxrwx 1 root root 22 may 19 2015 /usr/bin/java -> /etc/alternatives/java

manuel@zonademanel:~ ? ls -lah /etc/alternatives/java

lrwxrwxrwx 1 root root 39 dic 7 11:52 /etc/alternatives/java -> /usr/lib/jvm/java-8-oracle/jre/bin/java

I modified my /etc/environment file with the following values

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/lib/jvm/java-8-oracle/jre/bin" JAVA_HOME="/usr/lib/jvm/java-8-oracle/jre"

If I do not want to relogin I can reload the changes with:

source /etc/environment 

??And run mvn -version correctly

manuel@zonademanel:~ ? mvn -version

Apache Maven 3.0.5
Maven home: /usr/share/maven
Java version: 1.8.0_77, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-8-oracle/jre
Default locale: es_MX, platform encoding: UTF-8
OS name: "linux", version: "3.16.0-70-generic", arch: "amd64", family: "unix"

If you are using mac-OS , export JAVA_HOME=/usr/libexec/java_home need to be changed to export JAVA_HOME=$(/usr/libexec/java_home) . Steps to do this :

 $ vim .bash_profile

 export JAVA_HOME=$(/usr/libexec/java_home)

 $ source .bash_profile

where /usr/libexec/java_home is the path of your jvm

$JAVA_HOME should be the directory where java was installed, not one of its parts:

export JAVA_HOME=/usr/lib/jvm/java-7-oracle

It happens because of the reason mentioned below :

If you see the mvn script: The code fails here ---

Steps for debugging and fixing:

Step 1: Open the mvn script /Users/Username/apache-maven-3.0.5/bin/mvn (Open with the less command like: less /Users/Username/apache-maven-3.0.5/bin/mvn)

Step 2: Find out the below code in the script:

  if [ -z "$JAVACMD" ] ; then
  if [ -n "$JAVA_HOME"  ] ; then
    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
      # IBM's JDK on AIX uses strange locations for the executables
      JAVACMD="$JAVA_HOME/jre/sh/java"
    else
      JAVACMD="$JAVA_HOME/bin/java"
    fi
  else
    JAVACMD="`which java`"
  fi
fi

if [ ! -x "$JAVACMD" ] ; then
  echo "Error: JAVA_HOME is not defined correctly."
  echo "  We cannot execute $JAVACMD"
  exit 1
fi

Step3: It is happening because JAVACMD variable was not set. So it displays the error.

Note: To Fix it

export JAVACMD=/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/jre/bin/java

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home/

Key: If you want it to be permanent open emacs .profile

post the commands and press Ctrl-x Ctrl-c ( save-buffers-kill-terminal ).

Firstly, in a development mode, you should use JDK instead of the JRE. Secondly, the JAVA_HOME is where you install Java and where all the others frameworks will search for what they need (JRE,javac,...)

So if you set

JAVA_HOME=/usr/lib/jvm/java-7-oracle/jre/bin/java

when you run a "mvn" command, Maven will try to access to the java by adding /bin/java, thinking that the JAVA_HOME is in the root directory of Java installation.

But setting

JAVA_HOME=/usr/lib/jvm/java-7-oracle/

Maven will access add bin/java then it will work just fine.

In my case, the problem was in vscode.

I use windows and installed Ubuntu on my computer, so vscode terminal uses the Ubuntu. I just go to settings.json and change to cmd.exe again