1 public static void main(String[] args) {
 2             List<String> list = new ArrayList<String>();
 3             list.add("1");
 4             list.add("2");
 5             list.add("3");
 6             list.add("4");
 7             list.add("5");
 8             System.out.println("Original list : " + list);
 
 9             System.out.println();
10 
11             for (String temp : list) {
12                 System.out.println("Check for " + temp);
13                 if ("3".equals(temp)) {
14                     list.remove(temp);
15                 }
16             }
17 
18             System.out.println("Removed  list : " + list);
 
19         }

執行以上程式碼丟擲 java.util.ConcurrentModificationException 異常

public static void main(String[] args) {
            List<String> list = new ArrayList<String>();
            list.add("1");
            list.add("2");
            list.add("3");
            list.add("4");
            list.add(
 
"5");
            System.out.println("Original list : " + list);
            System.out.println();

            Iterator<String> iterator = list.iterator();
            while (iterator.hasNext()){
                String temp = iterator.next();
                System.out.println("Check for " + temp);
                if("3".equals(temp)){
                    iterator.remove();
                }
            }
            System.out.println("Removed  list : " + list);
        }

使用迭代器可以正常執行