Java final, abstract and static Modifiers

The meaning of the final, abstract and static Java modifiers can be confusing and hard to remember. Here's a brief summary:

final

Generally means "can't be changed".

• final class: can't be extended (sub-classed)
• final method: can't be overridden or hidden by sub-classes
• final variable: can only be initialized once 

abstract

Generally means "can't be instantiated".

• abstract class: can't be instantiated, can be extended, must be declared abstract if it contains one or more abstract methods
• abstract method: has only a declaration with no body
• abstract variable: not allowed

static

Generally means "not associated with an instance".

• static class: only nested inner classes can be static, they are not associated with any instance of the enclosing class
• static method: doesn't use instance variables
• static variable: is the same across all instances of it's containing class

additional notes

• constants: use static final as variable modifiers
• abstract static methods are not allowed