Homebrew 安装 Java8

brew tap adoptopenjdk/openjdk

brew cask install adoptopenjdk8

如果提示两个 tap 冲突，使用 untap 命令：

brew untap ... 

JAVA_HOME

编辑 .bash_profile，添加 JAVA_HOME:

# JDK 8
export JAVA_HOME_8=/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home 
export JAVA_HOME_13=/Library/Java/JavaVirtualMachines/openjdk-13.0.1.jdk/Contents/Home
export PATH=$PATH:$JAVA_HOME_8

alias jdk8="export JAVA_HOME=$JAVA_HOME_8"
alias jdk13="export JAVA_HOME=$JAVA_HOME_13"

刷新配置：

source ~/.bash_profile

或者如果是 zsh

source ~/.zshrc

切换版本

➜  ~ jdk8
➜  ~ java -version
openjdk version "1.8.0_242"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_242-b08)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.242-b08, mixed mode)

➜  ~ jdk13
➜  ~ java -version
openjdk version "13.0.1" 2019-10-15
OpenJDK Runtime Environment (build 13.0.1+9)
OpenJDK 64-Bit Server VM (build 13.0.1+9, mixed mode, sharing)

默认选择低版本Java

https://stackoverflow.com/questions/21964709/how-to-set-or-change-the-default-java-jdk-version-on-os-x

Solution without 3rd party tools:
leave all JDKs at their default location, under /Library/Java/JavaVirtualMachines. The system will pick the highest version by default.
To exclude a JDK from being picked by default, rename its Contents/Info.plist to Info.plist.disabled. That JDK can still be used when $JAVA_HOME points to it, or explicitly referenced in a script or configuration. It will simply be ignored by system's java command.
System launcher will use the JDK with highest version among those that have an Info.plist file.

When working in a shell with alternate JDK, pick your method among existing answers (jenv, or custom aliases/scripts around /usr/libexec/java_home, etc).