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

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

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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15. Suppose the class Employee is declared as follows: public class Employee { private String name; private double baseSalary: public void setName(String newName) {...} public void setBasSalary(double newSalary){...} public String getName() {...} public double getSalary({...} } a)Declare a class Manager that inherits from the class Employee and adds an instance variable bonus for storing a salary bonus. Omit constructors and methods. ANS: b) Which instance variables does the Manager class have? c) In the manager class, provide the method overrides the getSalary method from the class Employee so that it returns the sum of the salary and the bonus d) Based on the above question, which methods does the manager class inherit? e) In the manager class, override the getName method so that managers have a before their name (such as *John Smith).
An abstract class's parent class's abstract methods must all be implemented by its subclasses. Is it real or not?
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When should an abstract class be used, when should an interface be used, and when should both be used?
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Find the error in the following code segment: 1 2 |/ Superclass 3 public abstract class Vehicle 4- { public abstract double getKMPerlitre(); 7 (Other methods . . .) 8 } 10 11 12 // Subclass 13 public class Car extends Vehicle 14- { 15 private int distance; 16 public int getKMPerlitre() { return distance; } 17 18- 19 20 21 22 (Other methods .) 23 } 24 a. public abstract double getKMPerLitre(); should not end with a semicolon. O b. The getKMPerLitre method in the Car class should return a double. O c. The Car class cannot extend Vehicle class. O d. The Vehicle class should not be abstract.
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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?
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