Find all available JREs on Mac OS X from Java application installer

Question

If Java application requires certain JRE version then how can I check its availability on Mac OS X during installation?

Answer 1

It should be as simple as looking at /System/Library/Frameworks/JavaVM.framework/Versions/

Eg from my machine:

manoa:~ stu$ ll /System/Library/Frameworks/JavaVM.framework/Versions/
total 56
774077 lrwxr-xr-x  1 root  wheel    5 Jul 23 15:31 1.3 -> 1.3.1
167151 drwxr-xr-x  3 root  wheel  102 Jan 14  2008 1.3.1
167793 lrwxr-xr-x  1 root  wheel    5 Feb 21  2008 1.4 -> 1.4.2
774079 lrwxr-xr-x  1 root  wheel    3 Jul 23 15:31 1.4.1 -> 1.4
166913 drwxr-xr-x  8 root  wheel  272 Feb 21  2008 1.4.2
168494 lrwxr-xr-x  1 root  wheel    5 Feb 21  2008 1.5 -> 1.5.0
166930 drwxr-xr-x  8 root  wheel  272 Feb 21  2008 1.5.0
774585 lrwxr-xr-x  1 root  wheel    5 Jul 23 15:31 1.6 -> 1.6.0
747415 drwxr-xr-x  8 root  wheel  272 Jul 23 10:24 1.6.0
167155 drwxr-xr-x  8 root  wheel  272 Jul 23 15:31 A
776765 lrwxr-xr-x  1 root  wheel    1 Jul 23 15:31 Current -> A
774125 lrwxr-xr-x  1 root  wheel    3 Jul 23 15:31 CurrentJDK -> 1.5
manoa:~ stu$ 

Answer 2

This artical may help: http://developer.apple.com/technotes/tn2002/tn2110.html
Summery:

String javaVersion = System.getProperty("java.version");
if (javaVersion.startsWith("1.4")) {
  // New features for 1.4
}