I'm stuck on my homework, can I get some feedback? java

Question

package javaapplication1;


public class Main
  {

       public static void main(String[] args)
        {
        Student stu = new Student();
        System.out.println (stu.getStudentid() +":" + stu.getStudentname()+":"+stu.getStudentgrade());
//1:Bill:A
        Student stu2 = new Student ();
        System.out.println (stu2.getStudentid() +":" + stu2.getStudentname()+":"+stu2.getStudentgrade());

//2:Mary:B
        Student stu3 = new Student ();
        System.out.println (stu3.getStudentid() +":" + stu3.getStudentname()+":"+stu3.getStudentgrade());
//3:Jame:C
        Student stu4 = new Student ();
        System.out.println (stu4.getStudentid() +":" + stu4.getStudentname()+":"+stu4.getStudentgrade());
//4:Helen:D

        }
  }

        class Student
        {
            int Studentid;
            String Studentname;
            String Studentgrade;

            Student()
            {
                Studentid = 1;
                Studentname = "Bill";
                Studentgrade = "A";
            }


  int getStudentid()
  {
   return Studentid;
  }

  String getStudentname()
  {
    return Studentname;
  }
 String getStudentgrade()
  {
    return Studentgrade;
  }

}

Problem 1: Design and implement a Student class which has - Data members: studendID, studentName, and studentGrade - Constructor: Student (int id, String name) which will set studentID to the argument ‘id’ and studentName to the argument ‘name’ (studentID = id; studentName = name) - Method members: setGrade( ), getGrade ( ), getName( ), and getID( )

Problem 2: Implement a Test class which has a ‘main’ function. The ‘main’ function will create 4 student objects from the Student class above with ids and names: 1, Bill; 2, Mary; 3, Jame; 4, Helen and set their grades to A, B, C, D. The main ( ) function will output: ID:Name:Grade 1:Bill:A 2:Mary:B 3:Jame:C 4:Helen:D This is an example that he gave us.

class Cis36L0413
{
  public static void main( String[] args )
  {
    NotSimple nsObj1 = new NotSimple();

    System.out.println( "nsObj1.data is\t" + nsObj1.getData() );
    System.out.println( "nsObj1.str is \t" + nsObj1.getStr() );

    NotSimple nsObj2 = new NotSimple( 50,
                         "Another immutable string!" );
    System.out.println( "nsObj2.data is\t" + nsObj2.getData() );
    System.out.println( "nsObj2.str is \t" + nsObj2.getStr() );

    nsObj2 = nsObj1;

    System.out.println( "nsObj2.data is\t" + nsObj2.getData() );
    System.out.println( "nsObj2.str is \t" + nsObj2.getStr() );

    return;
  }
}
class NotSimple
{
  NotSimple()
  {
    data = 5;
    str = new String( "Initialized!" );
  }

  NotSimple( int i, String str1 )
  {
    data = 5;
    str = str1;
  }

  void setData( int i )
  {
    data = i;

    return;
  }

  int getData()
  {
   return data;
  }

  void setStr( String str1)
  {
    str = str1;

    return;
  }

  String getStr()
  {
    return str;
  }

  private int data;
  private String str;
}

1) How do I change the data so I can print out 2:Mary:B on the second line? and 3:Jame:C on the third and 4:Helen:D on the fourth? So far I am printing out 4lines of 1:Bill:A. 2) If I am doing this wrong, can you please give me some examples?

thank you in advance

Hi, I am just following up on this. This is the correct coding that he wanted.

package test;

public class Test {

    public static void main(String[] args) {
    Student stu1 = new Student(1,"Bill");
    stu1.setGrade ("A");
    System.out.println(stu1.getId()+":"+stu1.getName()+":"+ stu1.getGrade());
    Student stu2 = new Student (2,"Mary");
    stu2.setGrade ("B");
    System.out.println(stu2.getId()+":"+stu2.getName()+":"+ stu2.getGrade());
    Student stu3 = new Student (3,"Jame");
    stu3.setGrade ("C");
    System.out.println(stu3.getId()+":"+stu3.getName()+":"+ stu3.getGrade());
    Student stu4 = new Student (4,"Helen");
    stu4.setGrade ("D");
    System.out.println(stu4.getId()+":"+stu4.getName()+":"+ stu4.getGrade());

     }
}
    class Student{
    int studentId;
    String studentName;
    String studentGrade;

    Student(int id, String name){
        studentId = id; 
        studentName = name;     
    }
    public String getName(){
        return studentName;
    }
    public int getId(){
        return studentId;
    }
    void setGrade(String i)
  {
    studentGrade =i;
    return;
        }
    public String getGrade(){
    return studentGrade;
    }  
}

Answer 1

You need to create a Student constructor which takes three parameters: the name, the grade, and the ID, like this:

Student(int id, String name, String grade)
{
    Studentid = id;
    Studentname = name;
    Studentgrade = grade;
}

Alternately (I'm not sure if this is beyond the scope of what you're learned so far or not) you can have the ID number be automatically generated by using a static counter, and instead of having a 3-argument constructor, only write a constructor that takes two arguments. Just in case you haven't gotten that far, or aren't supposed to do that, I'll leave that code up to you.

Answer 2

You don't have Student (int id, String name) constructor and setter methods in your student class yet. Try to add them, have your main method initialize different student instances and go from there.

Answer 3

You are misunderstanding the instructions: You want a Student class and a Test class which implements the method of main.

public class Test {
}

not:

public class Main {
}

Also, you need a Student constructor as such:

Student(int id, String name, String grade)
{
    Studentid = id;
    Studentname = name;
    Studentgrade = grade;
}

Answer 4

Okay, I'll bite. Here are a couple of thoughts:

1. Your Student class is utterly wrong. There's no way to create a Student other than the default, and the defaults make no sense.
2. Why prepend each variable name in a Student class with "student"? Id, name, and grade will do.

More like this:

package student;

/**
 * Student
 * User: Michael
 * Date: Oct 8, 2010
 * Time: 9:08:17 PM
 */
public class Student
{
    private int id;
    private String name;
    private String grade;

    public Student(int id, String name)
    {
        this(id, name, "");
    }

    public Student(int id, String name, String grade)
    {
        this.id = id;
        this.name = name;
        this.grade = grade;
    }

    public int getId()
    {
        return id;
    }

    public String getName()
    {
        return name;
    }

    public String getGrade()
    {
        return grade;
    }

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

    public String toString()
    {
        return "Student{" +
               "id='" + id + '\'' +
               ", name='" + name + '\'' +
               ", grade='" + grade + '\'' +
               '}';
    }
}

And here's the test class:

package student;

/**
 * StudentTest
 * User: Michael
 * Date: Oct 8, 2010
 * Time: 9:09:29 PM
 */
public class StudentTest
{
    public static void main(String[] args)
    {
        List<Student> students = new ArrayList<Student>()
        {{
            add(new Student(1, "Bill", "A"));
            add(new Student(2, "Mary", "B"));
            add(new Student(3, "Jane", "C"));
            add(new Student(4, "Helen", "D"));
        }};

        for (Student s : students)
        {
            System.out.println(s);
        }
    }

}