java - Java BO 中的 ConcurrentModificationException

Question

我在此代码中遇到 java.util.ConcurrentModificationException，但似乎无法理解原因或修复它。

在 BO 中我有这个(权限是 BO 内的数组列表)

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

根据 ArrayList javadoc

The iterators returned by this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException.

for (BO bo : arraylist)

上面的 for-each 循环获取列表的 Iterator 和

  arraylist.add(newobj);

您尝试在不使用迭代器自己的方法的情况下修改列表，这会导致 ConcurrentModificationException

这里是SO discussion on possible solutions .