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Huron High School AP Computer Science Instructor: Kevin Behmer S. Teacher: Guillermo Moreno.

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Presentation on theme: "Huron High School AP Computer Science Instructor: Kevin Behmer S. Teacher: Guillermo Moreno."— Presentation transcript:

1 Huron High School AP Computer Science Instructor: Kevin Behmer S. Teacher: Guillermo Moreno

2 Inheritance How to establish inheritance relationships among classes? Code reuse can be achieved by this technique?

3 What is “extends”? What is variable hiding? Occurs when a variable in one class has the same name as a variable in a superclass.

4 Method overriding Occurs when a method in one class has the same type signature as a method in a superclass. What is run-time polymorphism?

5 The “super” keyword Used to invoke a superclass method or constructor. Public TokenTest() { super(“Testing Class”);...

6 Object Oriented Programming Inheritance allows one class to reuse the functionality provided by its superclasses. The extends clause in a class declaration establishes an inheritance relationship.

7 Syntax: class ClassName2 extends ClassName1 { // class body }

8 Objects: A class may directly extend only one superclass. However, it may have several subclasses. Each subclass may itself have several subclasses.

9 To declare a variable To declare a variable that references an object: ClassName variableName;

10 To summarize: A superclass reference can refer to an object of its class or any object derived from that class.

11 Class Burger { } class Hotdog extends Burger { } class Inheritance { public static void main(..) { Burger cheese; System.out.println(“Instantiating”); cheese = new Burger(); }

12 The super keyword The super keyword enables you to access the superclass variable and construct a subclass by using the same variable name. super.variableName;

13 class Korea { int pp = 48289037; } class Seoul extends Korea { int pp = 10331244 ; void display() { Sys.out.println(“pp=“ + pp); Sys.out.println(“pp=“ + super.pp); }

14 Class PopulationUpdate { public static void main(..) { Seoul pp = new Seoul(); pp.display(); } }

15 Output: pp = 10 331 244 pp = 48 289 037

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