Given the following definitions: public abstract class Manager extends Employee { . } public class Executive extends Manager { What, if anything, is wrong with the following code? public class hrSystem { } public void payRaise () { Manager m = } new Manager(); Compiles fine but will generate a run-time error unless an Employee object is created first. Compiler error because there is no Manager constructor. No problem. } Compiler error because Manager is abstract so an instance cannot be created.

A subclass of an abstract class must provide concrete implementations for each of the parent class's abstract methods in order to be considered a subclass. What are your thoughts on this?

Subclasses of abstract classes must implement the parent class's abstract methods. You think?

Given the following definitions: public abstract class Manager extends Employee {...} public class Executive extends Manager { ... } What, if anything, is wrong with the following code? public class hrSystem { } public void payRaise () { } Manager m = new Manager(); O Compiler error because there is no Manager constructor. Compiler error because Manager is abstract so an instance cannot be created. No problem. The code will compile without any errors. O Compiles fine but will generate a run-time error unless an Employee object is created first.

Class Relationships Exercises 1. In Java, we use inheritance for "is-a" relationships. Containment, on the other hand, indicates that one object has another object. These are "has-a" relationships. For the following relationships, determine if they are a "is-a" or a "has-a" relationship: o bicycle - vehicle o car - engine o pizza - topping o food - pizza o dog - mammal 2. Share with someone else 3 other examples for each of the following relationships: o Inheritance ("is-a" relationship) o Containment ("has-a" relationship) 3. public class PersonInfo { protected String firstName; protected String birthdate; } public class ChildInfo extends PersonInfo { private String schoolName; } public class MotherInfo extends PersonInfo { private String spousename; private ChildInfo children1; private ChildInfo children2; private ChildInfo children3; ... } A. Draw the relationships for the classes above using UML. If a class inherits from another class, draw an open arrow pointing to the base class…

When to declare abstract class?   Topic software engineering