Question

[Continued] Your Course class should have:

1)a getter for the course 'code', so that it is read-only;

2)a getter and setter for the lecturer attribute, so that it is readable and writable;

3)a constructor that creates the associations shown in the UML diagram;

4)an enrolStudent method that adds a given Student object into the 'enrolled' set;

5)a withdrawStudent method that removes a given Student object from the 'enrolled' set and returns true if the student was successfully found and removed, false otherwise.

Short Answer Questions Here is a Java interface for moving/resizing shapes. /** General interface to all kinds of geometric shapes. */ public interface MovableSizable /** Resize this shape. Example. 0.5 halves the size */ void resize(double scale); /** @return total height, rounded to the nearest pixel. */ intgetHeight); /** @return total width, rounded to the nearest pixel. */ int getWidth(); /**Move shape so it is centred on (xv). */ void move Tolint x, int y); int getX); int getX) Short Answer Questions Q1. [10 marks] Implementa class called Circle that implements the MovableSizable interface, and adds a constructor that takes two int values (the initial x.y centre of the circle) and one double value (the initial radius of the circle). For example, new Circle(100,200,3.5) would create a new circle centred at position (100,200) with diameter 7.0 pixels. Note that the constructor must throw an llegalArgumentException if the radius is zero or negative. Short Answer Questions Q2. [5 marks] Drawa UML class diagram of the MovableSizable interface and your Circle class, showing all the details of each class (e.g. methods, fields, constructors) Short Answer Questions Q3. [5 marks] Write a JUnit 5.0 test class, that has two tests of your Circle class: 1) one test that creates a circle at position (0,0) with radius 3.6, and checks that all the getter methods return the correct values (width and height are both 7 pixels and the x and y locations are both 0). Then it calls moveTo(10,20) and resize(3.0) and checks all the getter methods again (x should be 10, y should be 20, and width and height should both be 22 pixels, because 3.6*3*2=21.6, which rounds up to 22) 2) one test that tries to create a circle with radius of -2.0. The test should pass if this throws an exception, and fail if the circle is constructed without any errors. Short Answer Questions Q4. [10 marks] The following UML class diagram describes the structure of a Java program for managing university courses. Implement just the Course class by writing a Java class that implements it. You can assume that the Student and Staff classes have already been coded in Java and that they have getter methods for each data field. [see next page for more details] Course Student -id : int -code: String name: String +Student() +Course(code:String) enrolled enrolStudent(s:Student) +sitExamint +withdrawStudent(s: Student): boolean lecturer Staff name: String +Staff +markExams0

Answer 1

Hi, I have answered this question before. Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// Circle.java

public class Circle implements MovableSizable {

      //fields

      private int x, y;

      private double radius;

     

      //constructor

      public Circle(int x, int y, double radius) {

            if (radius <= 0) {

                  //invalid radius, throwing IllegalArgumentException

                  throw new IllegalArgumentException();

            }

            //initializing values

            this.x = x;

            this.y = y;

            this.radius = radius;

      }

      @Override

      public void resize(double scale) {

            //resizing radius by given scale

            radius *= scale;

      }

      @Override

      public int getHeight() {

            //rounding height and returning it

            return (int) Math.round(radius*2);

      }

      @Override

      public int getWidth() {

            //rounding width and returning it

            return (int) Math.round(radius*2);

      }

      @Override

      public void moveTo(int x, int y) {

            //updating x and y

            this.x = x;

            this.y = y;

      }

      @Override

      public int getX() {

            return x;

      }

      @Override

      public int getY() {

            return y;

      }

}

//UML diagram

Circle x: int y: int radius: double T Movable Sizable resize(double) void Circle(int,int,double) getHeight()int resize(double) void getWidth() int getHeight()int moveTo(int,int):void getWidth) int getx(int move To(int, int)void getX() int getY(0 int getY()int

// CircleTest.java

import static org.junit.Assert.*;

import org.junit.Test;

public class CircleTest {

      @Test

      public void test1() {

            // creating a circle. testing getter methods

            Circle circle = new Circle(0, 0, 3.6);

            assertEquals(circle.getX(), 0);

            assertEquals(circle.getY(), 0);

            assertEquals(circle.getHeight(), 7);

            assertEquals(circle.getWidth(), 7);

            // testing moveTo and resize methods

            circle.moveTo(10, 20);

            circle.resize(3.0);

            assertEquals(circle.getX(), 10);

            assertEquals(circle.getY(), 20);

            assertEquals(circle.getHeight(), 22);

            assertEquals(circle.getWidth(), 22);

      }

      @Test

      public void test2() {

            // ensuring that IllegalArgumentException is thrown when a negative or

            // zero radius is given as argument

            try {

                  Circle circle = new Circle(0, 0, -2);

                  fail("No exception thrown. Was expecting IllegalArgumentException");

            } catch (IllegalArgumentException e) {

            } catch (Exception e) {

                  fail("Should throw IllegalArgumentException, got: " + e);

            }

      }

}

// Course.java

import java.util.ArrayList;

public class Course {

      // attributes

      private String code; // course code

      private ArrayList<Student> enrolled; // list of students enrolled

      private Staff lecturer; // lecturer

      // (3)a constructor that creates the associations shown in the UML diagram

      public Course(String code) {

            this.code = code;

            // initializing list

            enrolled = new ArrayList<Student>();

      }

      // 1)a getter for the course 'code', so that it is read-only;

      public String getCode() {

            return code;

      }

      // 2)a getter for the lecturer attribute, so that it is readable

      public Staff getLecturer() {

            return lecturer;

      }

      // 2)a setter for the lecturer attribute, so that it is writable;

      public void setLecturer(Staff lecturer) {

            this.lecturer = lecturer;

      }

      // 4)an enrolStudent method that adds a given Student object into the

      // 'enrolled' set;

      public void enrolStudent(Student s) {

            // simply adding

            enrolled.add(s);

      }

      // 5)a withdrawStudent method that removes a given Student object from the

      // 'enrolled' set and returns true if the student was successfully found and

      // removed, false otherwise.

      public boolean withdrawStudent(Student s) {

            // finding the student

            for (int i = 0; i < enrolled.size(); i++) {

                  if (enrolled.get(i).getId() == s.getId()) {

                        // found, removing and returning true

                        enrolled.remove(i);

                        return true;

                  }

            }

            return false; // not found

      }

}