Arduino software won't open in Mac OSX 10.10.1 I am having trouble opening the Arduino software on my mac, since I have updated Java to version 8 the Arduino software won't open. It does not give an error just closes instantly.

I have tried getting the newest version of the Arduino.cc site but no change.

Can anyone tell me how to open Arduino using an older version of Java?
Download and install the Apple version of Java (6): http://support.apple.com/kb/DL1572

If you need Java 8 SDK for some reason, the two can coexist because the Arduino IDE will explicitly ask for the (Apple Version) of Java 1.6 using 'JavaApplicationStub':

$ ./JavaApplicationStub
[JavaAppLauncher] Requested [1.5*], launching in [1.6] instead.
Experimental:  JNI_OnLoad called.
Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version   = RXTX-2.1-7


Note however that if you have both Apple Java and Oracle installed, running 'java' or 'javac' form the command line will run the Oracle version.

$ java -version
java version "1.8.0_25"


If you need to switch the 'command line' version, change the symlinks in:

/System/Library/Frameworks/JavaVM.framework/Versions/


'JavaApplicationStub' will use the Apple version located in /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java.  

As such, 'normal' java programs will generally use the Oracle version, while applications running in your browser or using JavaApplicationStub explicitly (like Arduino) will use the 'Apple' version.