Thinking in Objects

1. Thinking in Objects Chapter 10

2. Immutable Objects and Classes • The String class is immutable. • How to make our Circle class immutable? • delete the set method! • radius is private, cannot be changed without a set method

3. Scope of Variables • class variable vs. local variable • publicclass Foo { • privateintx = 0; //Class variable • privateinty = 0; • publicvoid p(){ • intx = 1; //Local variable • System.out.println("x = " + x); • System.out.println("y = " + y); • } • }

4. The this Keyword • The this keyword is the name of a reference that refers to an object itself. • reference a class’s hidden data fields

5. The this Keyword • enable a constructor to invoke another constructor of the same class

6. Class Abstraction and Encapsulation • Class abstraction means to separate class implementation from the use of the class. • The detail of implementation is encapsulated and hidden from the user. • developer vs. user

7. The Loan Class • UML (Unified Modeling Language) diagram

8. The BMI (Body Mass Index) Class

9. The BMI Class • BMI = weight (in kilograms) / height2 (in meters) • BMI Interpretation • below 16 seriously underweight • 16-18 underweight • 18-24 normal weight • 24-29 overweight • over 29 seriously overweight