Install Oracle JDK 8 and switch between JDKs in Ubuntu 18.04
1. Check installed Open JDK
Note that by default Ubuntu 18.04 includes Open JDK 10 or 11. Check your current Java version first, or list the JDK package installed.
yao@DESKTOP:~$ sudo apt list --installed | grep jdk
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
openjdk-11-jdk/bionic-updates,bionic-security,now 10.0.2+13-1ubuntu0.18.04.4 amd64 [installed]
openjdk-11-jdk-headless/bionic-updates,bionic-security,now 10.0.2+13-1ubuntu0.18.04.4 amd64 [installed,automatic]
openjdk-11-jre/bionic-updates,bionic-security,now 10.0.2+13-1ubuntu0.18.04.4 amd64 [installed,automatic]
openjdk-11-jre-headless/bionic-updates,bionic-security,now 10.0.2+13-1ubuntu0.18.04.4 amd64 [installed,automatic]
2. Install Oracle JDK 8 (or 9)
Follow Install Oracle Java 8 / 9 in Ubuntu 16.04, Linux Mint 18. It also works in Ubuntu 18.04.
- Add PPA
sudo add-apt-repository ppa:webupd8team/java
- Install Oracle JDK 8 (or 9)
sudo apt update
sudo apt install oracle-java8-installer
sudo apt install oracle-java9-installer
- Now the
javac -verisonshould be switched to the new Oracle JDK 8 (or 9), but better check before we go on.
yao@DESKTOP:~$ javac -version
javac 1.8.0_201
- Set Java environment variables
yao@DESKTOP:~$ sudo apt install oracle-java8-set-default
Reading package lists... Done
Building dependency tree
Reading state information... Done
oracle-java8-set-default is already the newest version (8u201-1~webupd8~1).
oracle-java8-set-default set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 182 not upgraded.
3. Switch between JDKs
yao@DESKTOP:~$ 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-oracle/jre/bin/java 1081 manual mode
Press <enter> to keep the current choice[*], or type selection number:2
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