A method is an operation defining the behavior for a particular abstraction. Java implements abstractions using classes that have properties and behavior. Behavior is defined by the operations of the abstraction.
An object is an instance of a class. Objects are created from classes that implement abstractions. The objects that are created are concrete realizations of those abstractions. An object is neither a reference nor a variable.
(2) is the first line of a constructor declaration. A constructor in Java is declared like a method, but does not specify a return value. (1) is the header of a class declaration, (3) is the first statement in ...