Throwable Classes

Throwable + Throwable() + Throwable(String) + getMessage() : String + printStackTrace()
Error	Exception
VirtualMachineError	RuntimeException		IOException
StackOverflowError	ClassCastException	NullPointerException	SocketException	FileNotFoundException

Exceptions fall into three categories:

Errors	Very Serious Problems	VM prints stack and dies
RuntimeExceptions	Avoidable Exceptions	Not required to catch
Other Exceptions	Normal Exceptions	Must declare and catch