Mac install Java

# 这里会安装最新java version
$ brew cask install java
# 这里可以指定安装java version
$ brew cask install caskroom/versions/java8

# 然后执行下述命令
$ echo "alias setJdk8='export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)'" >> ~/.zshrc
$ echo "alias setJdk11='export JAVA_HOME=$(/usr/libexec/java_home -v 11)'" >> ~/.zshrc
# 这里默认指定java8
$ echo "export JAVA_HOME=`/usr/libexec/java_home -v 1.8`" >> ~/.zshrc
$ source ~/.zshrc

# 切换版本
$ setJdk8
$ java -version
java version "1.8.0_181"
Java(TM) SE Runtime Environment (build 1.8.0_181-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)

$ setJdk11
$ java -version
openjdk version "11.0.1" 2018-10-16
OpenJDK Runtime Environment 18.9 (build 11.0.1+13)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.1+13, mixed mode)

# 查看安装的javas
$ ls /Library/Java/JavaVirtualMachines
jdk1.8.0_181.jdk   openjdk-11.0.1.jdk