Assuming the Employee class has a sayName method that returns the employee's name (which is Fred), the Object class has no such method, and given the following code, what will be the output? Employee e = new Employee(); Object o=e; o.sayName(); O A compiler error because there is no sayName method in the Object class. O Nothing. The o object has not been assigned a name even though it inherits from Employee. O Fred, because "Object o=e;" makes "o.sayName();" equivalent to "e.sayName();" O A compiler error because you can't assign an Employee object to an Object reference variable.

Assuming the Employee class has a sayName method that returns the employee's name (which is Fred), the Object class has no such method, and given the following code, what will be the output? Employee e = new Employee(); Object o=e; o.sayName(); O A compiler error because there is no sayName method in the Object class. O Nothing. The o object has not been assigned a name even though it inherits from Employee. O Fred, because "Object o=e;" makes "o.sayName();" equivalent to "e.sayName();" O A compiler error because you can't assign an Employee object to an Object reference variable.

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

See similar textbooks

Similar questions

the class should be named Change. The class requires at least 2 instance variables for the name of a person and the coin change amount to be given to that person. In Australia, the coin denominationsare 50 cents, 20 cents, 10 cents, and 5 cents. All these instancevariables should be declared as private. Think of a way such that the client program can use thesame class name and public methods for other countries with different coin denominations withoutchanging their client program. Explain how your class can satisfy this in your externaldocumentation.Your class will need to have at least a default constructor, and a constructor with two parameters:one parameter being a name and the other a coin amount. Your class should also provide appropriateget and set methods for client usage. Other methods (including helper) may be provided as needed.However, make sure they are necessary for good class design; you must provide legitimate justification for their usage in the internal and external…
We have two classes, Person and Employee. Both have a field, firstName. We have instances of these objectsPerson p and Employee e. Both p and e have the same value for firstName, specifically, p.firstName = “joe”and e.firstName = “joe” Which of the following statements is necessarily true? Group of answer choices 1. p.equals(e) will return true because they contain the same firstName. 2. We don’t know if either class will have an equals method. 3. There is not enough information to tell what p.equals(e) will return. 4. p.equals(e) will return false but p == e will be true.
This question concerns writing a Student class to model a student's name, composed of a first name, middle name and last name. The Student class should meet the following specification:Class StudentA Student object represents a student. A student has a first name, middle name and last name.Methodspublic void setNames(String first, String middle, String last)// Set the first, middle and last names of this Student object.public String getFullName()// Obtain the full name of this Student with the middle name converted to an initial only.2Thinking of the problem in terms of testing, there are three requirements that must be met:1. The setNames() method sets the names stored in the object i.e. the values of firstName, middleName, lastName.2. The getFullName() method obtains the name of the student with the middle name converted to an initial only.3. The getFullName() method does not change anything – i.e. it does not modify the values of firstName, middleName, lastNameHINT: To start your…
Given this class, please add the requested methods in the designated spaces provided. Instance methods: a) Write two constructors that will initialize the instance variables for a Student instance as follows: 1) Write a constructor that takes in three parameters – an int, a String, and a double. The constructor will assign them to the ID, name, and GPA instance variables respectively. 2) Write a no-argument (zero-parameter) constructor that will set the ID to - 1, the name to “No name assigned”, and the GPA to –1.0. b) Write an accessor method for the name variable. c) Write a mutator method for the GPA variable. d) Write a toString() method that will display all three instance variables on a single line, with a | (vertical bar) character between each one. e) Write an equals() method that returns true only if all three instance variables are equal. public class Student { // declare instance variables here private int ID; private String name; private double GPA;
This question involves the design of a class that will be used to produce practice problems. The following StudyPracticeinterface represents practice problems that can be used to study some subject. public interface StudyPractice. { /**Returns the current practive problem */ String getProblem(); /** Changes to the next practice problem */ void nextProblem(); } The MultPractice class is a StudyPracticethat produces multiplication practice problems. A MultPractice object is constructed with two integer values: first integer and initial second integer. The first integer is a value that remains constant and is used as the first integer in every practice problem. The initial second integer is used as the starting value for the second integer in the practice problems. This second value is incremented for each additional practice problem that is produced by the class. For example, a MultPractice object created with the call new MultPractice (7, 3)would be used to create the practice…
Using JAVA Language Consider a Billing class that implements an interface Payable having a method getTotalPaymentAmount(). Besides this, you have a Doctor class with private instance variables (docID, docName, and docFee) and a public getDoc() method, Patient class with private instance variables (pName, pID, pDisease), Medicine class with private instance variables (medID, medName, medQty, medPrice), and MedicalTest class with private instance variables (testID, testName, testPrice). Each of these classes has the toString() method to display the information of its object. The Billing class is having "Has A" relationship with the other four classes (Doctor, Patient, Medicine, and MedicalTest) mentioned above. The getPaymentAmount() method of Billing class returns the total billing amount that includes doc fee, medicine cost, and medical test fee that a patient has to pay. After implementing these classes, you are required to do the following in the driver class: Create an ArrayList of…
Consider this scenario, a mehtod in some class needs to access a data field in another class, here are two possible implementations: public class Process { /* * Check if student qualifies for financial help */ void check(Student student) { //.... } /* * Check if student qualifies for financial help */ void check(double studentGPA) { //.... }} In class Process, which check method you think is better, why? In other words, should we pass the object to the method or just the data member it needs? Disucuss the Pros and Cons of each approach (if any). Assume class Student has a mehod called getGPA( ).
Given the method listed below: B Foo(B x){return x;} Which of the below statements are correct? Foo takes 1 argument Foo takes 2 argument Foo is a class B is a class B is a method Foo takes as argument any subclass of B Foo returns a value of class B If the argument x is of class D which is a subclass of B, Foo returns a value of class B If the argument x is of class D which is a subclass of B, Foo returns a value of class D If the argument x is of class D which is a subclass of B, there will be a type check error
1 - Student class Make a class student (in student.py) that stores the following information for a student: Name (name) Student number (student_nr) Points per assignment (points_per_assignment) Exam grade (exam_grade) a) Behind each point of information is the name of the parameter to the initializer method. Store this information from the parameters in the object attributes with the same name. b) Add a method course_points() which returns the number of course points the student has gotten. Example: mary = Student("Mary", 15789613, [10, 9, 8, 10, 9, 10], 9)print(mary.course_points()) > 121 The calculation of the course points is explained in the course overview, course setup slides (Links to an external site.) and the first lectureLinks to an external site.. c) Add a method grade() which returns a the final grade of the student, rounded to nearest half (upwards, 6.75 -> 7). As per regulations, a 5.5 becomes a 6. If the student did not pass both the assignments (>= 95…
tri1 and tri2 are instances of the Triangle class. Attributes height and base of both tri1 and tri2 are read from input. In the Triangle class, define instance method print_info() with self as the parameter to output the following in one line: 'Height: ' The value of attribute height ', base: ' The value of attribute base
Change the Fraction class so that its instance variables (numerator and denominator) are hidden (i.e. private). Check that the client class (after this change) will now not compile. Why does it not compile? Provide the changes to the Fraction class and the TestFraction class such that the program can work with the private instance variables by implementing appropriate accessor and mutator methods. import java.util.Scanner;//test programpublic class testfraction{public static void main(String[] args) {//create a Scanner objectScanner in = new Scanner(System.in);//create new fractionFraction frac = new Fraction();//declare numerator and denominatorint n=1,d;System.out.print("Enter Fraction's Numerator: ");//input numeratorn = in.nextInt();System.out.print("Enter Fraction's Denominator: ");//input denominatord = in.nextInt();//loop execute until the numerator is negativewhile(n>=0){//call input with n and dfrac.input(n, d);//call displayfrac.display();System.out.print("Enter…
Write a class called Circle that contains:a. Three private instance variables: radius (of the type double), color (of thetype String), and area (of type double).b. Two constructors - a default constructor with no argument (default value of radiusis 2.0, and color is Green) and a parameterized constructor, which initializes onlythe radius and the color variables.c. Getter and setter for the radius and color variables.d. Two public methods: calculateArea(), and getPerimeter, which return the areaand perimeter of a circle instance, respectively. Both methods have return.Then write a driver class that tests the Circle class. In the driver class, create two objectsof Circle class, one that tests the default constructor of the Circle class (here no user inputis required) and then get the color, radius, area, and perimeter of that object and displaythem. The second object should test the parameterized constructor (here you need to ask userto give you input to initialize the class variables).…