Question

I am getting a java.util.ConcurrentModificationException in this code and can’t seem to understand why, or fix it.

In the BO I have this (privileges is an arraylist inside the BO)

public void setPrivilegename(String privilegename) {
    this.privileges.add(privilegename); 
}

List<PrivilegeObjectBO> arraylist = new ArrayList<PrivilegeObjectBO>();if (rs != null)              {
    while (rs.next()) {        
        for (BO bo : arraylist) {
            if (bo.getRolepkey()==rs.getInt("ROLE_PKEY")) {                         
                bo.setPrivilegename(rs.getString("SP.NAME"));

            }else{
                BO newobj = new BO();
                newobj.setRolepriviledgepkey(rs.getInt("PRIVILEGE_PKEY"));
                newobj.setProticolpkey(protocol);                
                newobj.setPrivilegename(rs.getString("SP.NAME"));
                newobj.setRolepkey(rs.getInt("SRP.ROLE_PKEY"));
                arraylist.add(newobj);
            }
        }
    }
}

Answer 1

In java, you will always get a ConcurrentModificationException when you modify the Collection while you are iterating over it.

Possible solution: use a temporary Collection for added or deleted items, and add or delete those items after the iteration is done.