Question

Give an input file of student records in the following format:

<name>#<SID>#<major>#<GPA>

Smith Eugene#A9S65A#Chemistry#2.50
Brown Ezra#T56G0M#Business Administration#1.36
Brown Ferman#PI56T4#Accounting#2.68
Chavis Ertle#7HS56#Chemistry#3.00
Strickland DiChildersa#TWH54F#Business Administration#2.00
Stone Clark#BN78N3W#English#4.00
Childers Evelyn#U8M8N2#Criminal Justice#2.73
Stone Desmond#JHD9K2#Computer Science#3.23

Write a Java application to process the input file of student information. Design your solution using classes for student, student Database, and a driver class. Your application should output the average GPA and display the student list in the descending order of their GPA.

Answer 1

This Java application was done using Eclipse IDE Version: 2020-09 (4.17.0)

To create a new Java Application:

1. Open Eclipse IDE

2. Select a directory as workspace -> Click “Launch”

3. Click “File -> New -> Java Project”

4. In “New Java Project” dialog box, Enter the Project name as “StudentDatabaseProject” -> Click “Finish”

5. In “New module-info.java” dialog box, Click “Don’t Create”.

A new Java Project “StudentDatabaseProject” will be created

6. Right-click on “src” -> New -> Package

7. In “New Java Package” dialog box, Enter Name as Project -> Click Finish

8. Right-click on “Project” -> New -> Class

9. In “New Java Class” dialog box, Enter Name as “Driver” -> Click Finish

10. Right-click on “Project” -> New -> Class

11. In “New Java Class” dialog box, Enter Name as “Student” -> Click Finish

12. Right-click on “Project” -> New -> Class

13. In “New Java Class” dialog box, Enter Name as “StudentDatabase” -> Click Finish

Add the following code:

Driver.java

package Project;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.List;
import java.util.Scanner;

// The program starts here
public class Driver {
        public static void main(String[] args) throws FileNotFoundException {
                // Add the path of your .txt file here
                File file = new File("D:\\StudentDB.txt");
            Scanner sc = new Scanner(file);
            // A StudentDatabase object is created
            StudentDatabase sd1 = new StudentDatabase();
            // Reads each line in the .txt file
            while (sc.hasNextLine()){
                String inputEachLine = sc.nextLine(); // Holds each line
                // Each line is split with '#' and the value is stored in studInput of type String[]
                String[] studInput = inputEachLine.split("#"); 
                if(!studInput[3].equals("<GPA>")) { //This ignores the first line
                        // Student object is created for each value
                        Student s1 = new Student(studInput[0], studInput[1], studInput[2], Double.parseDouble(studInput[3]));
                        // Each Student Object is added to StudentDatabase
                        sd1.addStudObject(s1);
                }
            }
            // Calls the averageGPA method in StudentDatabase to get the average of all the student's GPA
            System.out.println("The average GPA of students is " + sd1.averageGPA() + "\n");
            // Gets the student's details of type Student object in a list by calling the method sortDescending in StudentDatabase
            List<Student> DescendingList= sd1.sortDescending();
            // Each student detail is printed in descending order of their GPA
            System.out.println("Student list is diplayed in descending order.");
        for(int i = 0; i < DescendingList.size(); i++) {
                System.out.println("Student {" + "name = " + DescendingList.get(i).getName() +
                                ", SID = " + DescendingList.get(i).getSID() + 
                                ", major = " + DescendingList.get(i).getMajor() + 
                                ", GPA = " + DescendingList.get(i).getGPA() + '}');
        }
            
        }
}

Student.java

package Project;
// Student class
public class Student {
        // Instance Private Variables name, SID, major and GPA
    private String name;
    private String SID;
    private String major;
    private double GPA;
    
    // Constructor Declaration of Student Class with parameters String name, String SID, String major, double GPA
    public Student(String name, String SID, String major, double GPA)
    {
        this.name = name;
        this.SID = SID;
        this.major = major;
        this.GPA = GPA;
    }
    
    // Getter and Setter methods of the variables
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSID() {
        return SID;
    }

    public void setSID(String SID) {
        this.SID = SID;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }

    public double getGPA() {
        return GPA;
    }

    public void setGPA(double GPA) {
        this.GPA = GPA;
    }
}

StudentDatabase.java

package Project;
import java.util.ArrayList;
import java.util.List;
// StudentDatabase Class
public class StudentDatabase {
        // Instance Private Variables studObject
        private List<Student> studObject;
        // Constructor Declaration of StudentDatabase Class
    public StudentDatabase() {
        this.studObject = new ArrayList<>();
    }
    // addStudObject with paramter studObj of type Student adds each object to the studObject instance variable
    public void addStudObject(Student studObj){
        this.studObject.add(studObj);
    }
    // averageGPA() finds the average of all the student's GPA in the studObject List
    public double averageGPA(){
        double sum = 0.0;
        for(int i = 0; i < this.studObject.size(); i++){
            sum += this.studObject.get(i).getGPA();
        }
        return sum / this.studObject.size();
    }
    // sortDescending() sorts the values in studObject List by descending order of their GPA
    public List<Student> sortDescending(){
        for(int i = 0 ; i < this.studObject.size(); i++)
        {
            for(int j = i+1 ; j< this.studObject.size();j++)
            {
                if(this.studObject.get(i).getGPA() < this.studObject.get(j).getGPA())
                {
                    Student temp = this.studObject.get(i);
                    this.studObject.set(i, this.studObject.get(j));
                    this.studObject.set(j, temp);
                }
            }
        }
        return this.studObject;
    }
 
}

OUTPUT: