Loop through the list of objects to get attribute.

[Kris Danielewski]

I have a class Student

 public Student(String nameIn,String surnameIn,String sNumberIn,
            int courseworkMarkIn,
            int examMarkIn)

and another class with list.

List<Student> StudentList = new ArrayList<Student>();

I am trying to loop through the List to find student == my Entered student number.

private static void option2(List<Student> StudentListIn, Student s1In)
        {
            Scanner sc = new Scanner(System.in);
            String number;
            int mark;
            System.out.println("Enter Student Number ");
            number = sc.next();
//loop missing here..
            if(s1In.getStudentNo().contains(number));
                System.out.print("Enter coursework mark : ");
                mark = sc.nextInt();
                s1In.setCourseWorkmark(mark);
    

How can i list through the list??

[Devaka Cooray]

Well, you can use a for-each loop for this purpose like below:

for(Student s: StudentList){
   if(s.getStudentNumber()==number){
   }
}

But this is not a good practice, because you can use Map classes instead of those List classes, so you can get the student quickly and in a smart-way without having a loop.

Devaka.

[Kris Danielewski]

hmm

  
 private static void option2(Student s1In,List<Student> StudentListIn)
        {
            Scanner sc = new Scanner(System.in);
            String number;
            int mark=0;
            System.out.println("Enter Student Number ");
            number = sc.next();
            for(Student s: StudentListIn){
            if(s.getStudentNo().contains(number)){
            s.enterMarkC();

}}
  public void enterMarkC()  //Student class
    {
        Scanner sc = new Scanner(System.in);
        System.out.println(" Enter coursework Mark: ");
        courseworkMark = sc.nextInt();
    }

  

I have problem , it repeats enterMarkC for every Student in the list, check for student numbber work...
Currently I am trying to set the attribute of Student class (courseworkMark) by user input.
Looking forward for help with it.

[Kris Danielewski]

Really need help with it , thanks...

[Brian Legg]

I would guess that what number equals after the statement "number = sc.next()" and what is returned by "if(s.getStudentNo().contains(number))" are not behaving the way you would like them to. Add some print statements to double check your input value and expected results. Also, I would add a break in your loop once you find the correct Student.

If this is for a class and you are allowed to go further I would definately use Devaka's suggestion to use a Map to make this much much easier. Each Student has a unique number... so you could skip the loop and find the correct Student in one statement using a Map.

HTH GL

[John de Michele]

Kris,

I'll third Brian and Devaka's suggestion to use one of the Map classes instead of a List. Lists are useful when ordering matters, like in a queue. Maps are much better when it comes to searching.

John.