What is a Runnable object and a Runnable argument?
A Runnable object is one that implements the Runnable interface, which is the type used to execute new threads. The Runnable interface only has one method, run(), which must be implemented by a Runnable class. In Java an argument is a primitive value or object reference that is passed to a constructor or method, defined in the method signature. A Runnable argument would be a constructor or method argument that is declared to be a Runnable type. The constructor of the Thread class is the most obvious example.
