Java™ How to Program, Seventh Edition

3.7. Initializing Objects with Constructors

As mentioned in Section 3.5, when an object of class GradeBook (Fig. 3.7) is created, its instance variable courseName is initialized to null by default. What if you want to provide a course name when you create a GradeBook object? Each class you declare can provide a constructor that can be used to initialize an object of a class when the object is created. In fact, Java requires a constructor call for every object that is created. Keyword new calls the class’s constructor to perform the initialization. The constructor call is indicated by the class name followed by parentheses—the constructor must have the same name as the class. For example, line 14 of Fig. 3.8 first uses new to create a GradeBook ...