Using forEach and RemoveIf if used together will it cause ConcurrentModificationException?

Question

I have three classes

 (With getters and Setters)

Student (Class)
   String studentName;
   int sid;
   List<Employee>

Employee (Class)
   String employeeName;
   int eid;
   List<Admin>

Admin (Class)
   String name;
   int adminId;

public class Testing {
public static void main(String arfs[]) {

    Admin admin = new Admin();
    Admin admin2 = new Admin();
    Employee employee = new Employee();
    Student student = new Student();

    List<Admin> adminList = new ArrayList<Admin>();
    List<Employee> empList = new ArrayList<>();

    admin.setName("AdminOne");
    admin.setAdminId(1);
    adminList.add(admin);

    admin2.setName("AdminTwo");
    admin2.setAdminId(2);
    adminList.add(admin2);

    employee.setEmployeeName("employeeOne");
    employee.setEid(4);
    employee.setAdmin(adminList);

    System.out.println("EMPLOYEE: "+employee.getAdmin());

    empList.add(employee);

    student.setStudentName("studentOne");
    student.setSid(9);
    student.setEmployee(empList);

    student.getEmployee().forEach(s -> {
        if(s.getEid()==4) {
            s.getAdmin().removeIf(p -> p.getName().equals("AdminTwo"));
        }
    });

    System.out.println("Student Name: "+student.getStudentName()+" EMP: "+student.getEmployee());


}
}

I am getting the output without any exceptions, but i would like to know is there any chance of getting "ConcurrentModificationException" from the above code...

When we iterate a collection and make modification in the same, we will get concurrent modification exception...

*When we iterate a collection and make modification in the same, we will get concurrent modification exception*: but that's not what you're doing. You're iterating on the employee list, and you remove from the admin list, a **different** collection. Note: your code is very hard to read for a simple, stupid reason: you don't respect the rules of English. student.getEmployee() should be named student.getEmployees(), with an s, because there are several employees: it returns a list of employees, not an Employee. — JB Nizet, Aug 02 '19 at 12:01
@JBNizet Iterating from Student --> get Employee --> getAdmin.removeIf(), since we are not iterating the admin List...no possibility of ConcurrentModificationException?... — JavaLearner1, Aug 02 '19 at 12:04
No, since you're rmoving from a different collection from the one you're iterating. — JB Nizet, Aug 02 '19 at 12:05

score 0 · Answer 1 · answered Aug 02 '19 at 21:24

0

It is impossible to get ConcurrentModificationException with forEach or enchanced for because it is impossible also to modify the list.

In your case you iterate employeeList, but you modify adminList.

answered Aug 02 '19 at 21:24

Dorin Simion

131
5

Using forEach and RemoveIf if used together will it cause ConcurrentModificationException?

1 Answers1