Thread: Need Help With My Sorting and Arrays

Hello everyone, I still learning java so I'm still not familiar with how to call and how to change from different classes and using arrays but right now I'm trying to create a simple code like a school system where there show all the student name list with a grade in all the classes there are in using arrays object to store the data. I don't want to use ArrayList so NO ArrayList.

and it seems that I don't know how to do it. I'm really stuck right now can anyone help me with my code.

I WANT MY OUTPUT TO BE LIKE THIS:-

=== SCHOOL LISTS ===

1. Class Thunder with Total grade: 146
2. Class Lightning with Total grade: 103.9
3. Class Sunrise with Total grade: 115.5

--------------------
Class: Sunrise
Class quantity: 5

Student1: James Shawn
Grade: 75
Student2: Ali Pole
Grade: 30.5
Student3: Tong Kim
Grade: 10

Total Grade: 115.5
------------------------
Class: Thunder
Class quantity: 5

Student1: Mark Lee
Grade: 65.5
Student2: James Mic
Grade: 20.4
Student3: James Mic
Grade: 18.0

Total Grade: 103.9
------------------------
Class: Lightning
Class quantity: 5

Student1: Luke Kim
Grade: 90
Student2: Noth Shawn
Grade: 44
Student3: Lex Wale
Grade: 12

Total Grade: 146

Do you want to go back to the selection function?
Press Y or N:
//if yes they will go back to the functionSelection
//if no they will ask users if they want to exit the systems.

Do you want to exit (Y or N):

//if yes they will exit the systems
//if no they will go back to the functionSelection.

---------------------------------------------------------------------------------------------------------------------------------------

The class should have an array class of 10 sizes but initialize with 5 pre-team set.
and the student is only set to have 20 sizes (mean 20 students per class can't be more than the number set)

BELOW ARE MY CODE:-

STUDENT CLASS

import java.util.Comparator;
 
public class Student {
 
    private String studentName;
    private int grade;
 
    public Student(String studentName, int score) {
        this.studentName = studentName;
        this.grade = grade;
    }
 
    public String toString() {
        return "\nStudent Name: " + studentName + "\nGrade: " + grade;
    }
 
    public String getStudentName() {
        return studentName;
    }
 
    public int getGrade() {
        return grade;
    }
 
    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }
 
    public void setGrade(int grade) {
        this.grade = grade;
    }   
}
 
//Sorting side
class sortGrade implements Comparator<Student> {
 
        @Override
        public int compare(Student a, Student b) {
        return (a.getGrade() - b.getGrade());
    }
}

-----------------------------------------------------------------------
CLASS CLASS

public class Class {
 
    Student[] student;
    private String className;
    private int classQuantity;
    private int totalGrade = 0;
 
    //add student to the class
     public void addNewStudent(String studentName, double grade) {
 
    }
 
    public double calculateTotalGrade() {
 
        for (Student students : student) {
            totalGrade += students.getGrade();
        }
        return Math.round(totalGrade * 10.0) / 10.0;
    }
 
    public Class(Student[] student,
            String className, int classQuantity) {
 
        this.student = student;
        this.className = className;
        this.classQuantity = classQuantity;
    }
 
    public Class(String className, int classQuantity) {
 
        this.className = className;
        this.classQuantity = classQuantity;
    }
 
    public String toString() {
        String studentList = " ";
 
        for (int i = 0; i < student.length; i++) {
            studentList += "\n\tStudent " + (i + 1) + ": " + student[i].getStudentName()
                    + "\n\tGrade: " + student[i].getGrade();
        }
 
        return "\nClass Name: " + className
                + "\nClass Quantity: " + classQuantity + "\n" + studentList;
    }
}

--------------------------------------------------------------------------------------
MAIN DRIVER CLASS

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;
 
public class MainDriver {
 
    private Object[] a;
 
    void printSort(Student[] sortList) {
        for (Object sort : a) {
            System.out.print(sort + " ");
        }
        System.out.println();
    }
 
    public static void main(String[] args) {
 
        int size = 10;
        Class[] classroom = new Class[size];
 
        Student[] studentList1 = {
            new Student("Tong Kim", 10),
            new Student("Ali Pole", 30),
            new Student("James Shawn", 75)};
 
        Student[] studentList2 = {
            new Student("James Mic", 20),
            new Student("Ho Kim", 18),
            new Student("Mark Lee", 65)};
 
        Student[] studentList3 = {
            new Student("Luke Kim", 90),
             new Student("Noth Shawn", 44),
             new Student("Lex Wale", 12)
        };
 
        classroom[0] = new Class(studentList1, "Sunrise", 20);
        classroom[1] = new Class(studentList2, "Thunder", 10);
        classroom[2] = new Class(studentList3, "Lightning", 5);
 
        Scanner input = new Scanner(System.in);
        boolean functionSelection = true;
 
       // Student[] SortList = studentList1;
 
        while (functionSelection) {
 
            System.out.println("=== SCHOOL SYSTEM === \n");
            System.out.println("[1] Add New Class");
            System.out.println("[2] Exit");
 
            System.out.print("\nChoose a function: ");
 
            //Check if it is other then number
            if (!input.hasNextInt()) {
                System.out.println(" \nChoose the existing number");
                input.nextLine();
                continue;
            }
 
            int choice = input.nextInt();
 
            String newClassName, searchClass, newName, addName;
            switch (choice) {
                case 1:
 
                    //Show School List
                    /*List all class, student, grade and the total grade
                    in ascending*/
 
                    System.out.println("=== SCHOOL LIST ===");
 
                   Student[] SortList = studentList1;
 
                   //Descending Order Arrays
 
                    Comparator<Student> descendingOrder;
                    descendingOrder = Collections.reverseOrder
                    (new sortGrade());
 
                    Arrays.sort(SortList, descendingOrder);
                    System.out.println(Arrays.toString(SortList) + "\n");
                case 2: 
                    System.exit(0);
                    break;
                default:
                    System.out.println(" \nChoose the existing number");
            }
        }
    }
}

Please help me with my code

What happens when you compile the program? Are there any errors? Please copy and paste them here.

If there are no compiler errors, what happens when you execute the program? Please copy and paste here the console from when you execute the program. Be sure to add some comments on the lines that are not what you want to see.

Please edit your post and wrap your code with code tags:

[code]
**YOUR CODE GOES HERE**
[/code]

to get highlighting and preserve formatting.

Ok, that looks better.
Starting with the first line in the desired out:

=== SCHOOL LISTS ===

I do not see anything in the code that prints that line. Where should that line and the following lines be printed?

Then looking at the current output I see a line that is NOT in the desired output:

=== SCHOOL SYSTEM ===

Do you get any warnings or errors when you compile the program? I get a warning that MUST be fixed for the program to work properly. Copy and post here any compiler messages you need help with.

There no errors

No, I am talking about a warning from the compiler. You need to be sure that all warnings are turned on to be displayed when the code is compiled so that the warning messages are displayed. This warning is important for the code to work properly. The error causes the program to end too soon.


I suggest that you work on one section at a time. Make the needed changes to print these lines:

=== SCHOOL LISTS ===

1. Class Thunder with Total grade: 146
2. Class Lightning with Total grade: 103.9
3. Class Sunrise with Total grade: 115.5

When those lines are printed, then move to the next set of lines.

Where is the data that is to be printed? What class has it? What array are those classes in?

Ok can you add some print statements that print those values out like shown in the desired output?

1. Class Thunder with Total grade: 146

The parts in dark red should come from the class. The other Strings are just text to be printed between the data from the class.

Where is the TEAM CLASS? I can not see it in the posted code? You should be sure to copy the correct names from the code when posting here so that it can be found in the code to know what you are talking about. Don't make up names. Use the names in the code.

Also what is MAIN DRIVE? I can not see anything like that in the code.


How much of the posted code did you write? How much was given to you?

Spelling and case is important for communication so that there is no confusion.
The class's name is Class, not CLASS. The main method is named main not MAIN.

What is post code?

posted code refers to the code that you have pasted into your inputs to this forum's thread.

it keeps on giving me errors

Please copy the full text and paste it here.

System.out.println(classroom.displayTeamWin());

Is the variable: classroom declared to hold a reference to the class with the displayTeamWin method?