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 ).