Yet another "non-static method cannot be referenced fro a static context" problem

[jazzermonty]

Hello again folks

Need a little help here. I'm having a problem with this code.

import java.util.*;
public class Student extends TutorGroup
{
   public static final int NUMBER_OF_TMAS = 2;
   
   private String name; // the student's name
   public int[] tmaMarks = new int[Student.NUMBER_OF_TMAS] ;
   private char grade;  // the student's final grade
    */
   public Student(String aName)
   {
      super();
      this.name = aName;
      //tmaMarks to be initialised here
      Arrays.fill(this.tmaMarks,0);
      this.grade = 'X';
   }
  public void setMark(int tma, int mark)
   {
      if (tma > tmaMarks.length)
      {
        int[] newTmaMarks = new int[tma];
        newTmaMarks[tma-1] = mark;
        tmaMarks = newTmaMarks;
      }
      else
      {
     tmaMarks[tma - 1] = mark;     
      }
   }   
   public int[] getMarks()
   {
      return this.tmaMarks;
   }
}

import java.util.*;
import ou.*;
public class TutorGroup
{
   /* instance variables */
   Map<String, Student> students; 
   Map<Character, Student> results; 
   int aInt = 0;
   /**
    * Constructor for objects of class TutorGroup
    */
   public TutorGroup()
   {      
      students = new HashMap<String, Student>();          
   }
   /* instance methods */
   public void addStudent(String name)
   {
     // students.put(name, Integer.parseInt(Arrays.toString(this.Student.getMarks())) );
     Student aStudent = new Student(name);
     students.put(name, aStudent);
   }
    public void enterMarksForTMA(int tma)
   {     
      Set<String> keys = students.keySet();
      if (tma > 5)
      {
         OUDialog.alert("Invalid TMA number");
      }
      else     
      {
           for (int i=0; i < 5;i++)      
         {   
         for(String allStudents : keys)
            {
            tma = Integer.parseInt(OUDialog.request("Enter TMA "  + (i + 1)  + " mark for " + allStudents)); 
             Student.setMark((i+1), tma); 
            }   
         }
      }
   }  
}

The issue lies with the line in the TutorGroup class

Student.setMark((i+1), tma);

I know what I'm doing isn't allowed in java, but what I can't work out is how to solve this. What I'm attempting to to is this. The TutorGroup class has to create a Map where the names of students act as the keys. The Map should contain instances of Student objects. The Class Student holds and array of marks. The TutorGroup Class should provide the array with the values provided by the method enterMarksForTMA(). The Student class will do some calculations on the marks then this should be applied to the Student object held in the Map refrenced by the key. How do I write the code to do that? I haven't the faintest idea.

BTW, the class TutorGroup is still incomplete as I can't overcome this sticking point. Any help would be greatly appreciated.

Thanks

[Onra]

Why does Student extend TutorGroup? This sounds wrong.

students.get(allStudents).setMark((i+1), tma);

?

[Fubarable]

I agree with Onra, Student should absolutely not extend TutorGroup.

then in this code, please look at the comments:

for(String allStudents : keys)  {
   tma = Integer.parseInt(OUDialog.request("Enter TMA "  + (i + 1)  + " mark for " + allStudents)); 
   // Student.setMark((i+1), tma);  // Don't do this!!
   // If you have a String, allStudents, and a HashMap<String, Student>, 
   // how can you extract the Student of interest?
}

[jazzermonty]

Why does Student extend TutorGroup? This sounds wrong.

students.get(allStudents).setMark((i+1), tma);

?

This^^ brilliant. Works brill. Also, not sure why Student extended TutorGroup, fix now.

However, I now have a new issue. The assignment states that the code must be able to handle more TMA marks than the final variable in Student

 public static final int NUMBER_OF_TMAS = 2;

hence the method:

 public void setMark(int tma, int mark)
   {
     // tma = TutorGroup.enterMarksForTMA(tma);
      if (tma > tmaMarks.length)
      {
        int[] newTmaMarks = new int[tma];
        newTmaMarks[tma-1] = mark;
        tmaMarks = newTmaMarks;
      }
      else
      {
     tmaMarks[tma - 1] = mark;     
      }
   }

The assignment specifically says that the method

   public void enterMarksForTMA(int tma)

should check that the tma value is valid, without knowing what the upper value of TMA is. Therefore, when I send the message

student.enterMarksForTMA(3);

the first time round, the code needs to understand that the Array in Student is of the size 3. Then, if I send a new message

student.enterMarksForTMA(4);

I should get an alert that states that the TMA number is invalid. Any pointers on how I can achieve this?
Thanks again for all your help.

[Onra]

the code needs to understand that the Array in Student is of the size 3.

With which method can you check the size of an array?