Error on opening Arduino on OS X 10.10.5

Development Tools IDE 1.x
1

After working on several sketches successfully on my iMac with OS10.10.5, I now get an error on trying to open

"Unable to load Java runtime environment".

Don't know how to deal with this...

Help

2

Try restarting your computer.

3

Tried restarting iMac and uninstalling/reinstalling Arduino. Still get message on launch "Unable to load Java runtime environment".