Java getTopStudent and getAverageScore using arrays

Question

I've been studying code on my own, and I got a problem that I do not know how to answer. I am given a student and classroom class, and from those two I need to be able to create a method for getTopStudent, as well as thegetAverageScore. **Edit: All of the code was given except for the two methods, I needed to create those 2. The thing is that I'm not sure if what I'm doing is correct.

  public class Student
{
private static final int NUM_EXAMS = 4;

private String firstName;
private String lastName;
private int gradeLevel;
private double gpa;

private int[] exams;
private int numExamsTaken;

public Student(String fName, String lName, int grade)
{
    firstName = fName;
    lastName = lName;
    gradeLevel = grade;
    exams = new int[NUM_EXAMS];
    numExamsTaken = 0;
}

 public double getAverageScore() //this is the method that I need to, but I'm not sure if it is even correct. 
{
    int z=0;
    for(int i =0; i<exams.length; i++)
    {
        z+=exams[i];
    }
    return z/(double) numExamsTaken;
}

public String getName()
{
    return firstName + " " + lastName;
}

public void addExamScore(int score)
{
    exams[numExamsTaken] = score;
    numExamsTaken++;
}

public void setGPA(double theGPA)
{
    gpa = theGPA;
}

public String toString()
{
    return firstName + " " + lastName + " is in grade: " + gradeLevel;
}

}

public class Classroom
{
    Student[] students;
    int numStudentsAdded;

public Classroom(int numStudents)
{
    students = new Student[numStudents];
    numStudentsAdded = 0;
}

public Student getTopStudent() //this is the other method I need to create
{
    int x=0;
    int y=0;
    for(int i =0; i<numStudentsAdded; i++)
    {
        if(x<students.getAverageScore())
        {
            x=students.getAverage();
            y++;
        }
    }
    return students[y];
}

public void addStudent(Student s)
{
    students[numStudentsAdded] = s;
    numStudentsAdded++;
}

public void printStudents()
{
    for(int i = 0; i < numStudentsAdded; i++)
    {
        System.out.println(students[i]);
    }
}

}

I have something down for each of them but it isn't running. I don't fully understand arrays yet, but this is apparently a beginner code using arrays. If anyone could help with what I need to do and tell me how arrays work, much would be appreciated.

You probably want to look at ArrayList instead of creating an Array of Students. One problem you're having is that your addStudent() method is not adding a new Student. — Glen Pierce, Apr 30 '17 at 02:27
@Edgar Flores you haven't specified the problem you're having? — Ousmane D., Apr 30 '17 at 02:30
Because it just makes the last Student in the Array = the Student they're "adding". As soon as they try to add more students than the Array got initialized to, they're going to have problems. — Glen Pierce, Apr 30 '17 at 02:30
http://stackoverflow.com/questions/1647260/java-dynamic-array-sizes — Glen Pierce, Apr 30 '17 at 02:38

score 0 · Accepted Answer · answered Apr 30 '17 at 03:24

getAverageScore() is a method of Student. But students is not a Student object, it's an array of Student objects. (And getAverage(), which you call inside the for loop, isn't a method at all.) An array is a separate object that contains other objects or primitives (like ints) in it. So students.getAverageScore() is not going to compile, because students doesn't have that method, each of its members (student[0], student[1], etc.) has it.

Try replacing the getTopStudent method with something like this:

public Student getTopStudent() //this is the other method I need to create
{
    int x=0; //this will contain the highest average
    int y=0; //this will be the index in the array of the highest scoring student

    for(int i =0; i<numStudentsAdded; i++)
    {
        int currentAverage = students[i].getAverageScore(); //run the getAverageScore() on the current student
        if(x<currentAverage) // compare it to the previous high average
        {
            x=currentAverage; // replace x with new high average
            y=i; //replace the index of the highest scoring student with current index i
        }
    }
    return students[y]; // so if the fifth student had the highest score, y would be 4
}

score 0 · Answer 2 · answered Apr 30 '17 at 04:36

So you are having trouble int the method public Student getTopStudent()

public Student getTopStudent() //this is the other method I need to create
{
double x= students[0].getAverageScore();
int y = 0;
for(int i=1;i<students.length;i++){
    if(x<students[i].getAverageScore()) {
        x = students[i].getAverageScore();
        y =i;
    }   
}
return students[y];
}

See if this helps

Java getTopStudent and getAverageScore using arrays

2 Answers2