Table of contents
  1. check if java is arm64
  2. find all installed JDKs.
  3. run a specified JDK command.
  4. set the JAVA_HOME environment variable
  5. Slow Java app



check if java is arm64

cat `which java` | file -

output

/dev/stdin: Mach-O 64-bit executable arm64
  • or
    /dev/stdin: Mach-O 64-bit executable x86_64
On Mac OS X 10.5 or later, we can use:
/usr/libexec/java_home
to return the location of the default JDK :
/Library/Java/JavaVirtualMachines/jdk-16.jdk/Contents/Home

find all installed JDKs.

/usr/libexec/java_home -V

Matching Java Virtual Machines (4):
16 (x86_64) "Oracle Corporation" - "OpenJDK 16-ea" /Library/Java/JavaVirtualMachines/jdk-16.jdk/Contents/Home
15.0.1 (x86_64) "UNDEFINED" - "OpenJDK 15.0.1" /usr/local/Cellar/openjdk/15.0.1/libexec/openjdk.jdk/Contents/Home
14.0.2 (x86_64) "AdoptOpenJDK" - "AdoptOpenJDK 14" /Library/Java/JavaVirtualMachines/adoptopenjdk-14.jdk/Contents/Home
1.8.0_275 (x86_64) "UNDEFINED" - "OpenJDK 8" /usr/local/Cellar/openjdk@8/1.8.0+275/libexec/openjdk.jdk/Contents/Home
/Library/Java/JavaVirtualMachines/jdk-16.jdk/Contents/Home

run a specified JDK command.

/usr/libexec/java_home -v1.8

/usr/local/Cellar/openjdk@8/1.8.0+275/libexec/openjdk.jdk/Contents/Home

set the JAVA_HOME environment variable

  • On macOS 10.15 Catalina and later, the zsh is the default Terminal shell, and we can in either ~/.zshenv or ~/.zshrc
  1. Confirm you have JDK by typing
    which java

    output -> /usr/bin/java

  2. Check you have the needed version of Java, by typing
    java -version
    JAVA_HOME is essentially the full path of the directory that contains a sub-directory named bin which in turn contains the java.
    For Mac OSX it is /Library/Java/Home
  3. Set JAVA_HOME
    ` export JAVA_HOME=/Library/Java/Home`
  4. echo $JAVA_HOME on Terminal to confirm the path
  • Note that this sets JAVA_HOME only for this session. If you want it to persist, you will have to add the command to your ~/.profile file
  1. vim .profile
  2. add this to the end of the .profile file:
    JAVA_HOME=/Library/Java/Home
    export JAVA_HOME;
  3. nano ~/.zshenv
  4. Add the following content
    export JAVA_HOME=$(/usr/libexec/java_home)
  5. Source the file and print the $JAVA_HOME
    source ~/.zshenv
    echo $JAVA_HOME
    output -> /Library/Java/JavaVirtualMachines/jdk-16.jdk/Contents/Home

Slow Java app

  1. you need to find the hostname of your Mac.
    You do this from System Preferences.
    Click the Sharing icon in System Preferences.

  2. You will see a box that shows the Computer Name, under that will be the hostname ending in .local
    That’s what you will need, so take note of it.
    In my case it was Enzyme.local

  3. The next step is to update your /etc/hosts file. This must be done as root, so at the Terminal, type in

      sudo vi /etc/hosts

    This will ask for your password…
    Add the hostname you noted from earlier at the end of lines that start with 127.0.0.1 and ::1.

    In the end this is what my /etc/hosts file looked like:

     127.0.0.1       TPLNK-BPAXTON3.local
 255.255.255.255 broadcasthost
 ::1             TPLNK-BPAXTON3.local`