public void searchOwner(List<Appointments> appts, String owner) {
    Appointments theOne = null;
    for (Appointments temp : appts) {
        if (owner.equalsIgnoreCase(temp.owner.name)) {
            System.out.println(temp.data);
            temp.setResolved(true);
        }
    }
}

public void checkRemoval() {
    for (Appointments appts : appointments) {
        if (appts.resolved == true) {
            appointments.remove(appts);
        }

//Iterator method used before enhanced for-loop
    public void checkRemovalI(){
    Iterator<Appointments> it = appointments.iterator();
    while(it.hasNext()){
        if(it.next().resolved = true){
            it.remove();
        }
    }
}

So far this is where I am encountering my problem. I am trying to check the arrayList of Appointments and see if the field (resolved) is set to true, however I am receiving an ConcurrentModification exception during the searchOwner method when trying to set resolved = to true. I've tried using an Iterator in checkRemoval instead of an enhanced for-loop however that didn't help either. I really only need to get the part where the appointment is set to true to work, the checkRemoval seemed to be working early before implementing the changing of the boolean resolved. Any help will be greatly appreciated, thank you.