An IBM Technote was published last week regarding IBM Notes 9.0.1 for MacOS and the Java 8 update 152 or higher. After this update, the Notes client on Mac doesn't respond to mouse or keyboard input which is less than helpful and almost not useful.
The workaround for the moment is to downgrade to Java 8 update 151, which appears to be the highest level that doesn't fail with Notes. To get the Java update, you need to go to the Oracle Java download archive site - http://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase8-2177648.html and choose the update 151 for Java 8 Runtime. An Oracle account is required to download.
After that, you need to uninstall the current Java version. To do this, go to /Library/Internet Plug-Ins and delete the JavaAppletPlugin.plugin. You'll be prompted for your admin password. One that's done, start the install of the download from the archive site and you're all set. Just don't update the Java plugin when it says there's a newer version available.
Here's a link to the IBM Technote.