Java 1.6 for Mac OSX

Java 1.6 is not installed as default. You can download it from the
Apple Developer Connection (ADC) from the download section(if you are a member of ADC).

when you type java at the command line, it invokes /usr/bin/java which is really a link to the Java Framework.

Java Link

cmar$ ls -la /usr/bin/java
lrwxr-xr-x 1 root wheel 74 Apr 30 08:41 /usr/bin/java -> /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java

Switching you default

If you want to switch your default then you need to either modify the link /usr/java/bin
sudo ln -s /System/Library/Frameworks/JavaVM.framework/Versions/1.6/Commands/java /usr/bin/java
You might have to do "rm /usr/java/bin" first to remove the link before creating a new one.

Or you can just create an alias in your ~/.bash_login
alias java=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Commands/java

Reference