arraylist没有适合list.add的方法（数组属于对象类型）

Question

    public StudentLottery() {
     ArrayList<Student> list = new ArrayList<Student>();
}



    public void addStudents() {

    Scanner keyboard=new Scanner(System.in);
    String input;
    String id;
    String name;
    Student s;
    System.out.println("Enter? (y or n):");
    input=keyboard.nextLine();
    while (!(input.equals("n"))){
        System.out.println("Name:");
        name=keyboard.nextLine();   
        System.out.println("ID:");
        id=keyboard.nextLine();
        s=new Student(name,id);
        if (!(list.contains(s)))
            list.add(s);//error
        System.out.println("Enter? (y or n):");
        input=keyboard.nextLine();
    }

}

error occurs on list.add(s), I thought arrayLists could accept any type of object, but this arraylist only likes strings, so I'm unsure what I should be doing to fix this, so that my arraylist will accept student objects

jcreator says no suitable add method found

Answer 1

The list you've declared in the StudentLottery constructor is a local variable, not a field. You can't access it beyond the scope of the constructor. Perhaps you meant:

private ArrayList<Student> list;  // i.e. list is a field

public StudentLottery() {
    this.list = new ArrayList<Student>();  // initialize list in constructor
}