When installing PyCharm on Yosemite, you’ll get an error about missing Java Runtime 1.6. In fact, Apple has removed the Java Runtime version 1.6 on Yosemite. Don’t worry – you can install Java 1.6 using Java for OX 2014-001 from Apple. I strongly recommend doing it that way. You could also download JDK 1.7 or 1.8, but in fact that would break the signatures for the app bundle and as a result, updates won’t work anymore. Read more about that in Jetbrain’s blog.
This may also apply to other IDEs based on IntelliJ, such as WebStorm etc.
Another side effect on using Java 1.6 for IntelliJ products is font hinting: While it works fine with 1.6, it looks horrible on 1.7 and 1.8. This has to do with some Apple-specific adjustments in their Java distributions. You may also find the UI having the pre-Yosemite UI elements (buttons for example). Maybe the latest Java JDK/JRE do not support the new UI elements yet. This applies to any Java versions to date (1.6 – 1.8u25).