The Java Language Specification, Third Edition

8.4.10 Examples of Method Declarations CLASSES
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RealPoint from outside the body of RealPoint, no matter what the type of the
variable we may use to hold the reference to the object. Thus, we see that fields
and methods behave differently: hiding is different from overriding.
8.4.10.5 Example: Invocation of Hidden Class Methods
A hidden class (static) method can be invoked by using a reference whose type
is the class that actually contains the declaration of the method. In this respect,
hiding of static methods is different from overriding of instance methods. The
example:
class Super {
static String greeting() { return "Goodnight"; }
String name() { return "Richard"; }
}
class Sub extends Super {
static String greeting() { return "Hello"; }
String name() { return "Dick"; }
}
class Test {
public static void main(String[] args) {
Super s = new Sub();
System.out.println(s.greeting() + ", " + s.name());
}
}
produces the output:
Goodnight, Dick
because the invocation of greeting uses the type of s, namely Super, to figure
out, at compile time, which class method to invoke, whereas the invocation of
name uses the class of s, namely Sub, to figure out, at run time, which instance
method to invoke.
DRAFT
8.4.10.6 Large Example of Overriding
Overriding makes it easy for subclasses to extend the behavior of an existing
class, as shown in this example:
import java.io.OutputStream;
import java.io.IOException;
class BufferOutput {
private OutputStream o;
BufferOutput(OutputStream o) { this.o = o; }