Since the update of Java 8u40 our OSX users have not been able to type anything into the application and the application also does not even gain focus. I have tried other Web Start examples and I have the same issue, so it isn’t just us.
I went to http://docs.oracle.com/javase/tutorial/deployment/webstart/examplesIndex.html and launched both Web Start demo’s on that page. I can double-click in the fields and it appears it wants to rename or edit text but the caret doesn’t show up and typing doesn’t work. Also, Finder (or whatever app I had touched last) is still on the Mac title/tool bar. Is anyone else seeing this?
Seeing the exact same thing with every webstart application I can find (including our own). We got a report from a customer that they could not log in to our application (because the JTextField doesn't get focus), also 8u40 on Yosemite. We have since reproduced it on two other Macs with Yosemite and 8u40. I have reported a bug to Oracle, and have not found any workarounds.
来源：https://stackoverflow.com/questions/28904317/java-8u40-on-os-x-yosemite