Unit 5 - Inheritance

Question 1

What is a “is a” relationship?

Answer 1

• important concept in object orientation and is classified as an inheritance relationship
• relationship expresses that a class A can be viewed as similar to a different class B
• it expresses that a class is a special type of another class

Question 2

What is a superclass?

Answer 2

• also called: “base class” or “derived class”
• is the designation for a class from which other classes are derived

Question 3

What is a subclass?

Answer 3

• more specific type of superclass
• have all the attributers of the superclass, but also define other attributes that are important for their own description

Question 4

What is inheritance?

Answer 4

• it is what allows information to be conveyed about things either generally or specifically while avoiding redundancy
• helps reduce repetition in design
• methods and associations of the superclass are shared
• not only form of the superclass, but also its behavior and its use its inherited

Question 5

How are Inheritances implemented in Java?

Answer 5

• implemented using Extension
• public class Book extends Product {}
• the inherited attributes and methods can be used like normal instance attributes and methods
• the inherited attributes receive the values from the superclass

Question 6

What is assignment compatiblity?

Answer 6

• variable of the type of a superclass can also be assigned sublass objects
• reversed its not possible
• the type of a variable decides which attributes and methods can be invoked
• used to ensure the loosest possible coupling of individual classses in large software systems

Question 7

What is overriding?

Answer 7

• process of implementing an inherited method
• methods can be overridden in sublasses by creating a method with the same signature and implementating a new method body
• if an instance of the sublass is generated and inherited attributes or methods are accessed, then the overridden versions are selected
• Java keyword: super allows superclass to be addressed and its attributes and methods can be accessed