Declarations, Initialization, and Scoping - SCJP Sun Certified Programmer for Java Platform SE6 - page 108

Using super in Constructors
Similar to how you can use the this keyword to invoke another constructor in the same
class, you can use the super keyword to invoke a constructor in the parent class. Using
super allows the child class to choose which parent class constructor gets executed. As
with the this keyword, any calls to super must be the fi rst line of code in your constructor
or the code will not compile.
The super Keyword
Don't confuse the use of super in a constructor with the super keyword that represents
the reference to an object's parent. Using super in a constructor is a different, unrelated
use of the super keyword.
Let's look at an example. The following NonFictionBook class is a child of the Book class
and invokes one of the constructors in Book using the super keyword on line 6:
1. //Book.java
2. public class Book {
3. public String title;
4. public Person author;
5. public String ISBN;
6.
7. public Book(String ISBN) {
8. this.ISBN = ISBN;
9. }
10.
11. public Book() {
12. title = “Unknown”;
13. author = null;
14. ISBN = “-1”;
15. }
16.}
1. //NonFictionBook.java
2. public class NonFictionBook extends Book {
3. public String subject;
4.