sudo add-apt-repository ppa：openjdk-r / ppa
sudo apt-get update
sudo apt install openjdk-11-jdk
sudo apt-get install openjdk-9-jdk
update-java-alternatives --list
sudo update-alternatives --config java
sudo update-alternatives --config javac
＃JAVA_HOME = / usr / lib / jvm / jdk1.8.0_221
JAVA_HOME = / usr / lib / jvm / java-11-openjdk-amd64
export PATH = $ JAVA_HOME / bin：$ PATH
export JAVA_HOME
export JRE_HOME
export PATH