how to prompt user to input array values and create a data type in java

Question

I am working on a java code where it should prompt the user to input the grades of N amount of students and it should output the highest grade, My code is working well but I want to give the user ability to enter the content of the array and I want to create a data type called Student for example for the array.

public class Test3 {
   static double grades[] = {85, 99.9, 78, 90, 98};
       
   static double largest() {
      int i;
      double max = grades[0]; 
      for (i = 1; i < grades.length; i++)
         if (grades[i] > max)
            max = grades[i];
        
      return max;
   }
   public static void main(String[] args) 
   {
      System.out.println("Highest grade is :  " + largest());
   }
}

Any help would be really appreciated.

Answer 1

First, you should create the Student class:

    public class Student {

        private double grade;

        // empty constructor
        public Student() {}
        
        // all args constructor
        public Student(double grade) {
            this.grade = grade;
        }

        public double getGrade() {
            return grade;
        }

        public void setGrade(double grade) {
            this.grade = grade;
        }

        @Override
        public String toString() {
            return "Student{" +
                    "grade=" + grade +
                    '}';
        }
    }

To avoid repetitive code, you can use the Lombok library. It creates for you the constructors, getters, setters, toString(), and much more.

After, you can create a method to input students grades.

    public static Student[] inputStudens() {
        Scanner sc = new Scanner(System.in);
        System.out.println("How many students?");
        int N = sc.nextInt();

        Student[] students = new Student[N];
        for (int i=0; i<N; i++) {
            System.out.println("What's the grade for student " + i + ":");
            double grade = sc.nextDouble();
            Student student = new Student(grade);
            students[i] = student;
        }

        return students;
    }

And... using your already made max finder, but returning the Student instead.

    public static Student maxGrade(Student[] students) {
        int max = 0;
        for (int i = 1; i < students.length; i++) {
            if (students[i].getGrade() > students[max].getGrade()) {
                max = i;
            }
        }
        return students[max];
    }

Now we just need to call these methods in main().

    public static void main(String[] args) {
        Student[] students = inputStudens();
        Student student = maxGrade(students);
        System.out.println("Student with highest grade is: " + student);
    }

Answer 2

You can create an object and use that object to invoke the array to store value. For example:

test3obj= new Test3(); // creating an object.

Use test3obj to invoke the array to store values like:

test3obj.grades[i]=(object of scanner class).nextDouble();

Object of scanner class:

Scanner obj=new Scanner(System.in);