Question: I upgraded my OS X to Yosemite and now my IntelliJ IDE is not starting.

Here is the error message:

> 
> To open “IntelliJ IDEA” you need to install the legacy Java SE 6 runtime.
> 
> 
>

Answer: 
If you have latest JDK, you could change info.plist to handle this.

edit Info.plist file, in your jdk, for example:

```
/Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Info.plist

```

update JVMCapabilities dictionary to have following values:

```
          <key>JVMCapabilities</key>
            <array>
                    <string>CommandLine</string>
                    <string>JNI</string>
                    <string>BundledApp</string>
                    <string>WebStart</string>
                    <string>Applets</string>
            </array>

```

Now, try restarting the app. The application should now make use of the your JDK instead of looking for JDK 6
OSX has its JDKs in the folder `/Library/Java/JavaVirtualMachines/`.
There can be multiple versions there, for e.g. 1.7 or 1.8.

As indicated by @CrazyCoder, IntelliJ needs a 1.6 version to be present there, which Yosemite kicked out (in favor of a 1.7 if I'm not mistaken).

To install jdk 1.6, you can indeed simply use the [dmg from apple](http://support.apple.com/kb/DL1572?viewlocale=en_US&locale=en_US) as recommended by @CrazyCoder and confirmed by @LanceP.

As a [homebrew cask](http://caskroom.io/) user, I installed via

```
brew tap caskroom/versions
brew cask install java6

```

After this, IntelliJ was up and running again.

See also this [useful post](http://hanxue-it.blogspot.ca/2014/05/installing-java-8-managing-multiple.html) on managing multiple Java versions on OSX.