On Lubuntu 18.04, I though I am using Java 10, because
$ javac -version
javac 10.0.2
$ java -version
openjdk version "10.0.2" 2018-07-17
OpenJDK Runtime Environment (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.4)
OpenJDK 64-Bit Server VM (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.4, mixed mode)
But I am not sure, because I seem to use Java 11. I am confused. Thanks.
$ sudo update-alternatives --config java
There are 2 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1101 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1101 manual mode
2 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1081 manual mode
Press <enter> to keep the current choice[*], or type selection number:
$ sudo update-alternatives --config javac
There are 2 choices for the alternative javac (providing /usr/bin/javac).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/lib/jvm/java-11-openjdk-amd64/bin/javac 1101 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/javac 1101 manual mode
2 /usr/lib/jvm/java-8-openjdk-amd64/bin/javac 1081 manual mode
Press <enter> to keep the current choice[*], or type selection number:
$ realpath /usr/bin/java
/usr/lib/jvm/java-11-openjdk-amd64/bin/java
$ realpath /usr/bin/javac
/usr/lib/jvm/java-11-openjdk-amd64/bin/javac
