Develop a java program to define an abstract class Sum containing two abstract methods: int sumoftwo(int, int) int sumofthree(int, int, int) and a regular method, void display() Define a class Demo, that extends Sum class and implements all the methods. Also take an example to demonstrate the use of all the methods.

In Java, which of the following is false? An abstract class may implement an interface. A class that contains an abstract method must be declared abstract itself or a compiler message will result. A class may implement multiple interfaces. A class that extends another class may implement only one interface.

Using Java an elevator simulator that uses polymorphism and object-oriented programming tosimulate the movement of elevators in a building with multiple types of passengers and elevators.The system has 8 elevators, each of which can be one of 4 types of elevators, with a certainpercentage of requests for each type. Similarly, each passenger can be one of 4 types, with adifferent percentage of requests for each type. Passenger Types:There are 4 types of passengers in the system:Standard: This is the most common type of passenger and has a request percentage of 70%.Standard passengers have no special requirements.VIP: This type of passenger has a request percentage of 10%. VIP passengers are given priorityand are more likely to be picked up by express elevators.Freight: This type of passenger has a request percentage of 15%. Freight passengers have largeitems that need to be transported and are more likely to be picked up by freight elevators.Glass: This type of passenger has a request…

Java Program Write an abstract Java class named Vehicle.  It has two attributes grade(private) and roadTax(public) with types respectively String and double types. The constructor of Vehicle class initializes grade and roadTax with 'this' reference keyword. There is one abstract method named double totalTax() . The classes that extend Vehicle are PublicVehicle and PrivateVehicle which have the following attributes. Observe that the subclasses have overridden totalTax() method. For a PublicVehicle totalTax is= 2* (fitnessTax+roadTax) and for a PrivateVehicle, totalTax is= 2.5* (fitnessTax+roadTax+10.2)   class PublicVehicle extends Vehicle{private double fitnessTax;PublicVehicle(String grade, double roadTax, double fitnessTax) { //assign the variables}@Overridedouble totalTax() { //calculate total tax and return the value.}}class PrivateVehicle extends Vehicle{private double fitnessTax;PrivateVehicle(String grade, double roadTax, double fitnessTax) { //assign the…

Write a program in Java to perform the followings, (i) Design one parent and two child classes. Names of parent and child classes along with the names of their variables and methods should be taken from real-life by yourself. Parent class should have at least two variables, one parameterized constructor and one method to perform any meaningful operation/calculation with the variables. Child classes should have at least one additional variable declared within (ii) (iii) them and one parameterized constructor, and a toString method. (iv) Design another class and a main method inside it. Declare at least one object of each of the two child classes using parameterized constructor. Call the method of the parent class with these objects to perform the particular operation/calculation on these objects and show the result. Display values of all the variables of these objects using toString. Write the Java program using Eclipse IDE, copy and paste the code along with the output in a word file.…

Programing language is Java. Define a class Person that represents a person. People have a name, an age, anda phone number. Since people always have a name and an age, your class shouldhave a constructor that has those as parameters. Define a toString() method whichdisplays all of the relevant information using a format like this: “Jim Lahey - Age 57- Phone 9025555555”.

First, you need to design, code in Java, test and document a base class, Student. The Student class will have the following information, and all of these should be defined as Private: A first name (given name) A last name (family name/surname) Student number (ID) – an integer number (of type long) The Student class will have at least the following constructors and methods: (i)  two constructors - one without any parameters (the default constructor), and one with parameters to give initial values to all the instance variables of Student. (ii)  only necessary set and get methods for a valid class design. (iii)  a reportGrade method, which you have nothing to report here, you can just print to the screen a message “There is no grade here.”. This method will be overridden in the respective child classes. (iv)  an equals method which compares two student objects and returns true if they have the same student number (ID), otherwise it returns false. You may add other…