一. 安装:

sudo apt install openjdk-11-jdk
sudo apt install openjdk-8-jdk

二. 切换版本:

​sudo update-alternatives --config java​​​​java -version​​ 具体示例如下所示:

zjq@DESKTOP-2RLT53L:$ 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 1111 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 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: 2
update-alternatives: using /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java to provide /usr/bin/java (java) in manual modezjq@DESKTOP-2RLT53L:java$ java -version
openjdk version "1.8.0_282"
OpenJDK Runtime Environment (build 1.8.0_282-8u282-b08-0ubuntu1~18.04-b08)
OpenJDK 64-Bit Server VM (build 25.282-b08, mixed mode)
zjq@DESKTOP-2RLT53L:$ 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 1111 auto mode
1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 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: 1
update-alternatives: using /usr/lib/jvm/java-11-openjdk-amd64/bin/java to provide /usr/bin/java (java) in manual mode
zjq@DESKTOP-2RLT53L:$ java -version
openjdk version "11.0.10" 2021-01-19
OpenJDK Runtime Environment (build 11.0.10+9-Ubuntu-0ubuntu1.18.04)
OpenJDK 64-Bit Server VM (build 11.0.10+9-Ubuntu-0ubuntu1.18.04, mixed mode, sharing)
zjq@DESKTOP-2RLT53L:$ 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 1111 auto mode
* 1 /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1111 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: 2
update-alternatives: using /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java to provide /usr/bin/java (java) in manual modezjq@DESKTOP-2RLT53L:java$ java -version
openjdk version "1.8.0_282"
OpenJDK Runtime Environment (build 1.8.0_282-8u282-b08-0ubuntu1~18.04-b08)
OpenJDK 64-Bit Server VM (build 25.282-b08, mixed mode)
zjq@DESKTOP-2RLT53L:java$