I want to install a specific JDK (the latest for example). For this, I went to the JDK download homepage: http://java.sun.com/javase/downloads/index.jsp. I looked for a Mac
There are various tricky issues with having multiple versions of Java (Apple's own Java 6 and Oracle JDK 7 or even 8) on one's Mac OS X system, and using different versions for different applications. I spent some time writing up my experience of my experience of installing and configuring various versions of JDK on Mac OS X 10.9.2.
Since most answers are out of date, here's what works as of end of 2018 under the assumption that
In that case, grab the desired version from one the many available, freely usable OpenJDK editions, e.g.:
Some of these include installers, but if not you can do the following. Assuming here version 11.0.1 for Mac. In your favorite shell, run:
tar -xzf openjdk-11.0.1_osx-x64_bin.tar.gz
sudo mv jdk-11.0.1.jdk /Library/Java/JavaVirtualMachines
# Fix owner and group
sudo chown -R root:wheel /Library/Java/JavaVirtualMachines/jdk-11.0.1.jdk
# (Optional) Check if the new JDK can be found
/usr/libexec/java_home
=> /Library/Java/JavaVirtualMachines/jdk-11.0.1.jdk/Contents/Home
[0] Note that the Oracle branded JDK has significant licensing restrictions allowing you its use basically only for testing, i.e., not for production. If you do not have a support agreement with Oracle, then it seems risky to me to use their JDK, especially since the differences to OpenJDK are minimal.
Edit: added more choices
In a comment under @Thilo's answer, @mobibob asked how to set JAVA_HOME in your .bash_profile on a Mac. Answer:
export JAVA_HOME=`/usr/libexec/java_home`
This will dynamically assign to JAVA_HOME the location of the first JDK listed in the "General" tab of "Java Preferences" utility.
See Apple Technical Q&A 1170: https://developer.apple.com/library/content/qa/qa1170/_index.html
EDIT:
If you prefer parentheses to backticks for command substitution, this also works:
export JAVA_HOME=$(/usr/libexec/java_home)
As a rule you cannot install other versions of Java on a Mac than those provided by Apple through Software Update. If you need Java 6 you must have a 64-bit Intel computer. You should always have Java 5 and 1.4 and perhaps 1.3 installed if you have at least OS X 10.4.
If you have VERY much elbow grease and is willing to work with beta software you can install the OpenJDK under OS X, but I don't think you want to go there.
For people using any LION OS X 10.7.X
They uploaded Java SE 6 version 1.6.0_26 available here
http://support.apple.com/kb/dl1421
I bought a MacBook Pro yesterday (Mac OS X v10.8 (Mountain Lion)) and there is no JDK installed by default...
As well as javac, I also found it didn't have packages such as SVN installed. It turns out you can get everything from the Apple developer page (you will need to register with your AppleID). SVN is part of the "Command Line Tools" package.
This is what happens on a fresh MacBook:
Hopefully this will help out other newbies like me ;)