Java™ How To Program (Early Objects), Tenth Edition

Calling Method maximum

In main (lines 6–14), line 9 calls maximum with the integers 3, 4 and 5. When the compiler encounters this call, it first looks for a maximum method that takes three arguments of type int. There’s no such method, so the compiler looks for a generic method that can be used and finds generic method maximum. However, recall that the arguments to a generic method must be of a reference type. So the compiler autoboxes the three int values as Integer objects and specifies that the three Integer objects will be passed to maximum. Class Integer (package java.lang) implements the Comparable<Integer> interface such that method compareTo compares the int values in two Integer objects. Therefore, Integers are valid arguments to method ...