Thread: constructor and class

I'm trying to tackle the problem step by step. What I am having trouble is where to start lol
I started with writing the constructor but not sure if i'm going in the right direction for this problem. Seems pretty simple to me in concept. But I am getting errors so i must not be working it out right? Any pointers would be great

/*
63. Write a class encapsulating the concept of student grades on a test,
assuming student grades are composed of a list of integers between
0 and 100.
Write the following methods:
❑ A constructor with just one parameter, the number of stu-
dents; all grades can be randomly generated
❑ Accessor, mutator, toString, and equals methods
❑ A method returning an array of the grades sorted in ascending
order
❑ A method returning the highest grade
❑ A method returning the average grade
❑ A method returning the median grade (Hint: The median grade
will be located in the middle of the sorted array of grades.)
❑ A method returning the mode (the grade that occurs most
often) 
* 
* (Hint: Create an array of counters; count how many
times each grade occurs; then pick the maximum in the array
of counters; the array index is the mode.)
Write a client class to test all the methods in your class.
 */
package natashaepperson_chapter_08_exercise_63;
import java.util.Random;
 
 
 
public class Student 
{
//array random grades
private int []grades;
private String [] counters = { "How many times grade occurs",
                               "Max Grade", };
 
     //constructor with just one parameter, the number of students; all grades can be randomly generated                              
public StudentGrades()
{
    grades = new int[grade.lenght];
    fillGrades();
}
}

I think I understand, I get a little lost in some of the naming conventions. I haven’t had as much time to devote to java as I’d like to since I’m taking Calc III at the same time.

public class StudentGrades
{
//array random grades
private int []grades;
private String [] counters = { "How many times grade occurs",
                               "Max Grade", };
 
     //constructor with just one parameter, the number of students; all grades can be randomly generated                              
public StudentGrades()
{
    grades = new int[grade.lenght];
    fillGrades();
}
}

Doesn’t this make the class and constructor naming redundant?

Okay, how does this look now? I'm adding more to the code

package natashaepperson_chapter_08_exercise_63;
import java.util.Random;
/**
 *
 * @author Natasha.Epperson
 */
public class StudentGrade 
{
//array random grades
private int []grades;
private String [] counters = { "How many times grade occurs",
                               "Max Grade", };
 
     //constructor with just one parameter, the number of students; all grades can be randomly generated                              
public StudentGrades()
{
    grades = new int[grades.length];
    fillGrades();
}
/* method generatotes Grade Member IDs 
*  stores in array
*/
private void fillGrade()
{
    Random rand = new Random ();
    for (int i = 0; i < grades.length; i++)
    {
        grades[i] = rand.nextInt ()+1;
 
    }
}    
}

Originally Posted by nepperso

Okay, how does this look now? I'm adding more to the code

package natashaepperson_chapter_08_exercise_63;
import java.util.Random;
/**
 *
 * @author Natasha.Epperson
 */
public class StudentGrade 
{
//array random grades
private int []grades;
private String [] counters = { "How many times grade occurs",
                               "Max Grade", };
 
     //constructor with just one parameter, the number of students; all grades can be randomly generated                              
public StudentGrades()
{
    grades = new int[grades.length];
    fillGrades();
}
/* method generatotes Grade Member IDs 
*  stores in array
*/
private void fillGrade()
{
    Random rand = new Random ();
    for (int i = 0; i < grades.length; i++)
    {
        grades[i] = rand.nextInt ()+1;
 
    }
}    
}

Above code will result in nullpointerexception when an object to StudentGrades is created as you are trying to access the length of grades before initialization.