public class LabProgram {public static void main(String args[]) {Course cis162 = new Course(); int beforeCount; String toDrop; // Example students for testing cis162.addStudent(new Student("Henry", "Nguyen", 3.5)); cis162.addStudent(new Student("Brenda", "Stern", 2.0)); cis162.addStudent(new Student("Lynda", "Robison", 3.2)); cis162.addStudent(new Student("Sonya", "King", 3.9)); toDrop = "Stern"; beforeCount = cis162.countStudents(); cis162.dropStudent(toDrop); System.out.println("Course size: " + beforeCount + " students");System.out.println("Course size after drop: " + cis162.countStudents() + " students");} }import java.text.DecimalFormat; // Class representing a studentpublic class Student { private String first; // first nameprivate String last; // last nameprivate double gpa; // grade point average // Student class constructorpublic Student(String f, String l, double g) {first = f; // first namelast = l; // last namegpa = g; // grade point average} public double getGPA() {return gpa;} public String getLast() {return last;} // Returns a String representation of the Student object, with the GPA formatted to one decimalpublic String toString() {DecimalFormat fmt = new DecimalFormat("#.0");return first + " " + last + " " + fmt.format(gpa);}} **Task Instruction:**Complete the Course class in the file `Course.java` by implementing the `dropStudent()` method, which removes a student (by last name) from the course roster. If the student is not found in the course roster, no student should be dropped. Assume all students have distinct last names.**Given Classes:**- **Class LabProgram** contains the main method for testing the program.- **Class Course** represents a course, which contains an ArrayList of Student objects as a course roster. (Type your code in here.)- **Class Student** represents a classroom student, which has three private fields: first name, last name, and GPA. (Hint: `getLast()` returns the last name field.)**Note:** For testing purposes, different student values will be used.**Example:**For the following students:```Henry Nguyen 3.5Brenda Stern 2.0Lynda Robison 3.2Sonya King 3.9```The output for dropping Stern is:```Course size: 4 studentsCourse size after drop: 3 students``` This image displays a Java program source file named `Course.java`. The code defines a `Course` class which manages a list of `Student` objects using an `ArrayList`. Below is a transcription and explanation:```java1 import java.util.ArrayList; 2 3 public class Course {4 private ArrayList roster; // Collection of Student objects5 6 public Course() {7 roster = new ArrayList();8 }9 10 public void dropStudent(String last) {11 /* Type your code here */12 }13 14 public void addStudent(Student s) {15 roster.add(s);16 }17 18 public int countStudents() {19 return roster.size();20 }21 }```### Explanation:1. **Import Statement (Line 1):** - `import java.util.ArrayList;` imports the `ArrayList` class from the Java utility package, which is used for dynamic arrays.2. **Class Definition (Line 3):** - `public class Course {` begins the definition of the `Course` class.3. **Attributes (Line 4):** - `private ArrayList roster;` declares a private `ArrayList` named `roster` to store `Student` objects.4. **Constructor (Lines 6-8):** - `public Course() { roster = new ArrayList(); }` initializes the `roster` with a new `ArrayList` when a `Course` object is constructed.5. **Methods:** - **`dropStudent(String last)` (Lines 10-12):** Placeholder for a method intended to remove a student by their last name from the roster. The implementation is not provided (`/* Type your code here */`). - **`addStudent(Student s)` (Lines 14-16):** Adds a `Student` object `s` to the `roster`. - **`countStudents()` (Lines 18-20):** Returns the number of students currently in the `roster` using `roster.size()`.This simple class serves as a basic implementation for managing students within a course using Java's `ArrayList`. Further implementation details would be needed for complete functionality, especially in the `dropStudent` method.

The Course class has an instance variable roster which is an ArrayList of Student objects.The Course…

Answered: public class LabProgram { public static…

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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Question

public class LabProgram {

public static void main(String args[]) {

Course cis162 = new Course();

int beforeCount;

String toDrop;

// Example students for testing

cis162.addStudent(new Student("Henry", "Nguyen", 3.5));

cis162.addStudent(new Student("Brenda", "Stern", 2.0));

cis162.addStudent(new Student("Lynda", "Robison", 3.2));

cis162.addStudent(new Student("Sonya", "King", 3.9));

toDrop = "Stern";

beforeCount = cis162.countStudents();

cis162.dropStudent(toDrop);

System.out.println("Course size: " + beforeCount + " students");

System.out.println("Course size after drop: " + cis162.countStudents() + " students");

}

import java.text.DecimalFormat;

// Class representing a student

public class Student {

private String first; // first name

private String last; // last name

private double gpa; // grade point average

// Student class constructor

public Student(String f, String l, double g) {

first = f; // first name

last = l; // last name

gpa = g; // grade point average

}

public double getGPA() {

return gpa;

}

public String getLast() {

return last;

}

// Returns a String representation of the Student object, with the GPA formatted to one decimal

public String toString() {

DecimalFormat fmt = new DecimalFormat("#.0");

return first + " " + last + " " + fmt.format(gpa);

}

**Task Instruction:**

Complete the Course class in the file `Course.java` by implementing the `dropStudent()` method, which removes a student (by last name) from the course roster. If the student is not found in the course roster, no student should be dropped. Assume all students have distinct last names.

**Given Classes:**

- **Class LabProgram** contains the main method for testing the program.
- **Class Course** represents a course, which contains an ArrayList of Student objects as a course roster. (Type your code in here.)
- **Class Student** represents a classroom student, which has three private fields: first name, last name, and GPA. (Hint: `getLast()` returns the last name field.)

**Note:** For testing purposes, different student values will be used.

**Example:**

For the following students:

```
Henry Nguyen 3.5
Brenda Stern 2.0
Lynda Robison 3.2
Sonya King 3.9
```

The output for dropping Stern is:

```
Course size: 4 students
Course size after drop: 3 students
```

This image displays a Java program source file named `Course.java`. The code defines a `Course` class which manages a list of `Student` objects using an `ArrayList`. Below is a transcription and explanation:

```java
1 import java.util.ArrayList;
2
3 public class Course {
4 private ArrayList<Student> roster; // Collection of Student objects
5
6 public Course() {
7 roster = new ArrayList<Student>();
8 }
9
10 public void dropStudent(String last) {
11 /* Type your code here */
12 }
13
14 public void addStudent(Student s) {
15 roster.add(s);
16 }
17
18 public int countStudents() {
19 return roster.size();
20 }
21 }
```

### Explanation:

1. **Import Statement (Line 1):**
- `import java.util.ArrayList;` imports the `ArrayList` class from the Java utility package, which is used for dynamic arrays.

2. **Class Definition (Line 3):**
- `public class Course {` begins the definition of the `Course` class.

3. **Attributes (Line 4):**
- `private ArrayList<Student> roster;` declares a private `ArrayList` named `roster` to store `Student` objects.

4. **Constructor (Lines 6-8):**
- `public Course() { roster = new ArrayList<Student>(); }` initializes the `roster` with a new `ArrayList` when a `Course` object is constructed.

5. **Methods:**

- **`dropStudent(String last)` (Lines 10-12):**
Placeholder for a method intended to remove a student by their last name from the roster. The implementation is not provided (`/* Type your code here */`).

- **`addStudent(Student s)` (Lines 14-16):**
Adds a `Student` object `s` to the `roster`.

- **`countStudents()` (Lines 18-20):**
Returns the number of students currently in the `roster` using `roster.size()`.

This simple class serves as a basic implementation for managing students within a course using Java's `ArrayList`. Further implementation details would be needed for complete functionality, especially in the `dropStudent` method.

Expert Solution

Step 1: Algorithm

The Course class has an instance variable roster which is an ArrayList of Student objects.
The Course class has a constructor that initializes the roster ArrayList.
The dropStudent method removes a student with a specified last name from the roster.
The addStudent method adds a student to the roster.
The countStudents method returns the number of students in the roster.
The main method creates a Course object (cis162), adds four students to it, and then removes a student with the last name "Stern" using the dropStudent method.

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