switch the default java version code example

Example 1: change default java version mac

nano ~/.zshrc

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8.0)

Example 2: change java version

/usr/libexec/java_home -V  
export JAVA_HOME=`/usr/libexec/java_home -v 1.6.0_65-b14-462` //java 8