我们使用/usr/libexec/java_home它允许我们指定我们想要运行的java版本。因此，即使你安装了N个javas，它也应该返回带有标志的最高值。

   #!/bin/bash 
              ##### THIS IS CHECKING FOR JAVA 8 #####
   TMP_PATH=`/usr/libexec/java_home -F -v 9`

   if [ -z "$TMP_PATH" ] ; then

              ##### THIS IS CHECKING FOR JAVA 8 #####
     TMP_PATH=`/usr/libexec/java_home -F -v 1.8`

     if [ -z "$TMP_PATH" ] ; then
       osascript -e 'tell app "System Events" to display dialog "SQL Developer requires a     minimum of Java 8. \nJava 8 can be downloaded from:\n http://www.oracle.com/technetwork    /java/javase/downloads/"'
       exit 1
     fi
   fi