Fix java version for Flutter

I had some issues with building Android applications in Flutter. With the following as error message:

FAILURE: Build failed with an exception.

* Where:
Build file 'android/build.gradle'

* What went wrong:
Could not compile build file 'android/build.gradle'.
> startup failed:
  General error during semantic analysis: Unsupported class file major version 61

  java.lang.IllegalArgumentException: Unsupported class file major version 61

Install java 1.8

brew install --cask temurin8

The following java versions is now installed:

$ /usr/libexec/java_home -V
Matching Java Virtual Machines (3):
    17.0.1 (arm64) "Eclipse Temurin" - "Eclipse Temurin 17" /Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home
    1.8.0_322 (x86_64) "Eclipse Temurin" - "Eclipse Temurin 8" /Library/Java/JavaVirtualMachines/temurin-8.jdk/Contents/Home

Run flutter build apk either with inline variable as:

JAVA_HOME="$(/usr/libexec/java_home -v1.8)" flutter build apk

Or (more preferrable) export the variable with:

export JAVA_HOME="$(/usr/libexec/java_home -v1.8)"
# export PATH=$JAVA_HOME/bin:$PATH   # this might be needed
flutter build apk

Et volià ✓ Built build/app/outputs/flutter-apk/app-release.apk (46.0MB)..

References:

• Upgrade to OpenJDK Temurin using Homebrew