export JAVA_HOME=/usr/local/java6 # or /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home on macOS export PATH=$JAVA_HOME/bin:$PATH java -version Use jenv or /usr/libexec/java_home -v 1.6 :
"C:\Program Files\Java\jdk1.6.0_45\bin\java" -jar yourLegacyApp.jar java 1.6.0 download
If you just need to run an old .jar file, try using Java 8 first. It is much safer and still compatible with most Java 6 programs. You can download Java 8 from Adoptium . java 1.6.0 download
java -source 1.6 -target 1.6 -Djava.security.manager=allow -jar yourapp.jar (However, this does not work for apps that rely on removed internal APIs.) java 1.6.0 download
java -version