List数组遍历删除

环境

• jdk8
• junit 单元测试

正解

1// 正解1, jdk自带的addAll方法
2	@Test
3    public void test18() {
4        String[] strs = {"12","34","56","78","90"};
5        List<String> list = Arrays.asList(strs);
6        List<String> list2 = new ArrayList<>();
7        list2.addAll(list);
8        System.out.println(list);
9        for (String s : list) {
10            System.out.println(s);
11            list2.remove(s);
12        }
13    }
14
15// 正解2 Hutool的 CollUtil 工具类中addAll方法
16	@Test
17    public void test18() {
18        String[] strs = {"12","34","56","78","90"};
19        List<String> list = Arrays.asList(strs);
20        List<String> list2 = new ArrayList<>();
21        CollUtil.addAll(list2,list);
22        System.out.println(list2);
23        for (String s : list) {
24            System.out.println(s);
25            list2.remove(s);
26        }
27	}
28
29boolean b = list1.removeIf(a -> (a % 2) == 0);
30        System.out.println(b);

错解

新手代码踩坑日记

1// 第一错
2	@Test
3	public void test18() {
4	     String[] strs = {"12","34","56","78","90"};
5	     List<String> list = Arrays.asList(strs);
6	     System.out.println(list);
7	     for (String s : list) {
8	         System.out.println(s);
9	         list.remove(s);
10	     }
11	}
12
13报错信息:
14
15[12, 34, 56, 78, 90]
1612
17
18java.lang.UnsupportedOperationException  不支持的操作异常
19	at java.util.AbstractList.remove(AbstractList.java:161)
20	at java.util.AbstractList$Itr.remove(AbstractList.java:374)
21	at java.util.AbstractCollection.remove(AbstractCollection.java:293)
22
23
24// 第二错 : 老子新建个对象来存还是错??? 仔细想想-->TMD谁写的垃圾代码,好像是我写的...
25// 方法栈里面就一个list对象,只是复制一份引用,而remove是直接操作数组内存空间
26 	@Test
27    public void test18() {
28        String[] strs = {"12","34","56","78","90"};
29        List<String> list = Arrays.asList(strs);
30        List<String> list2 = new ArrayList<>();
31        list2 = list;
32        System.out.println(list);
33        for (String s : list) {
34            System.out.println(s);
35            list2.remove(s);
36        }
37    }
38
39直接报错 +1:
40[12, 34, 56, 78, 90]
4112
42
43java.lang.UnsupportedOperationException
44	at java.util.AbstractList.remove(AbstractList.java:161)
45	at java.util.AbstractList$Itr.remove(AbstractList.java:374)
46	at java.util.AbstractCollection.remove(AbstractCollection.java:293)
47