This post goes over how to use the “java” command-line tool on macOS.

Problem

Apple’s Java is a legacy version:

which java # /usr/bin/java

When you try to use java in the CLI:

java -version

You will get the pop-up:

To use the "java" command-line tool you need to install a JDK.

Solution

Install Java with Homebrew:

brew install java

Once it’s installed, look at Caveats:

==> Caveats
For the system Java wrappers to find this JDK, symlink it with
  sudo ln -sfn /usr/local/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk

openjdk is keg-only, which means it was not symlinked into /usr/local,
because macOS provides similar software and installing this software in
parallel can cause all kinds of trouble.

If you need to have openjdk first in your PATH, run:
  echo 'export PATH="/usr/local/opt/openjdk/bin:$PATH"' >> ~/.zshrc

For compilers to find openjdk you may need to set:
  export CPPFLAGS="-I/usr/local/opt/openjdk/include"

You can either symlink the JDK with:

sudo ln -sfn /usr/local/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk

Or export the openjdk first in your PATH:

echo 'export PATH="/usr/local/opt/openjdk/bin:$PATH"' >> ~/.zshrc

If you’re not using ZSH, make sure to replace ~/.zshrc with your shell configuration file.

Reload your shell profile:

source ~/.zshrc

Check the java binary and version:

which java # /usr/local/opt/openjdk/bin/java

java -version