Question

Create a class called Student which stores

• the name of the student

• the grade of the student

• Write a main method that asks the user for the name of the input file and the name of the output file. Main should open the input file for reading . It should read in the first and last name of each student into the Student’s name field. It should read the grade into the grade field.

• Calculate the average of all students’ grades.

• Open the output file, for writing, and print all the students’ names on one line and the average on the next line.

• Average should only have 1 digit after the decimal

• “Average” should be left justified in a field of 15 characters. The average # should be right justified in a field of 10 spaces

Sample input:

Minnie Mouse 98.7

Bob Builder 65.8

Mickey Mouse 95.1

Popeye SailorMan 78.6

Output:

Minnie Mouse, Bob Builder, Mickey Mouse, Popeye SailorMan

Average:       84.5

How can I fix my code to get the same output

public class Student {
public static void main(String[] args)throws IOException{
Scanner k=new Scanner(System.in);
String name;
float grade;
float Average=(float) 0.0;
float sum=(float) 0.0;
  
System.out.println("Enter input file name:");
String input=k.nextLine();
System.out.println("Enter output file name:");
String output=k.nextLine();
  
PrintWriter pw = new PrintWriter("students.txt");
pw.print("Minnie Mouse 98.7\nBob Builder 65.8\nMickey Mouse 95.1\nPopeye SailorMan 78.6\n");
pw.close();
PrintWriter pw2 = new PrintWriter("students2.txt");
pw2.print("Donald Duck 77.77\nTweety Bird 55.555\nCharlie Brown 95.231\n");
pw2.close();
/* End of creating the input file */
while(k.hasNext())
{
name=k.next();
grade=k.nextFloat();
Average+=grade;
sum++;
System.out.printf("name, ", name);
}
grade=Average/sum;
System.out.printf("\n%-15s%10.1f","Average", grade);   
/* test output file */
Scanner testOutput = new Scanner(new File("average.txt"));
while(testOutput.hasNext())
System.out.println(testOutput.nextLine());
/* end of test output file */
}
}
  

Answer 1

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. If not, PLEASE let me know before you rate, I’ll help you fix whatever issues. Thank

Note: The average will be 84.6 not 84.5. Because the actual average is 84.55, formatting to 1 digit after decimal point will automatically round it to 84.6

//Student.java

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;

public class Student {
        // attributes
        private String name;
        private double grade;

        // constructor taking name and grade
        public Student(String name, double grade) {
                this.name = name;
                this.grade = grade;
        }

        // getters for name and grade

        public String getName() {
                return name;
        }

        public double getGrade() {
                return grade;
        }

        // helper method to create input files dynamically, if you want
        private static void createInputFiles() throws FileNotFoundException {
                PrintWriter pw = new PrintWriter("students.txt");
                pw.print("Minnie Mouse 98.7\nBob Builder 65.8\nMickey Mouse 95.1\nPopeye SailorMan 78.6\n");
                pw.close();
                PrintWriter pw2 = new PrintWriter("students2.txt");
                pw2.print("Donald Duck 77.77\nTweety Bird 55.555\nCharlie Brown 95.231\n");
                pw2.close();
        }

        // main method
        public static void main(String[] args) throws IOException {
                Scanner sc = new Scanner(System.in);
                String name;
                double grade, sum, avg;

                // uncomment below statement if you want to create input files
                // (students.txt, students2.txt) dynamically.

                // createInputFiles();

                // asking, reading input & output file names

                System.out.println("Enter input file name:");
                String inFile = sc.nextLine();

                System.out.println("Enter output file name:");
                String outFile = sc.nextLine();

                // creating a list of Student objects
                ArrayList<Student> students = new ArrayList<Student>();

                // reinitializing scanner to read from file
                sc = new Scanner(new File(inFile));
                // looping through file
                while (sc.hasNext()) {
                        // reading next two strings to create single name
                        name = sc.next() + " " + sc.next();
                        // reading next number to store grade
                        grade = sc.nextDouble();
                        // creating a Student object with this name and grade, adding to
                        // list
                        students.add(new Student(name, grade));
                }
                // closing file
                sc.close();

                sum = 0;
                // opening output file
                PrintWriter writer = new PrintWriter(new File(outFile));
                // looping through the list
                for (int i = 0; i < students.size(); i++) {
                        // adding grade to sum
                        sum += students.get(i).getGrade();
                        // printing student name to output file followed by ', ' if
                        // necessary
                        writer.print(students.get(i).getName());
                        if (i != students.size() - 1) {
                                writer.print(", ");
                        }
                }
                // finding average
                avg = sum / students.size();
                // displaying average with proper formatting. (label is formatted with
                // 15 character wide field left justified, average formatted to 1 digit
                // after decimal, in a field of length 10, right justified)
                writer.printf("\n%-15s%10.1f\n", "Average:", avg);
                // closing file, saving changes
                writer.close();
        }
}

/*OUTPUT*/

Enter input file name:
students.txt
Enter output file name:
output.txt

/*output.txt*/

Minnie Mouse, Bob Builder, Mickey Mouse, Popeye SailorMan
Average:             84.6