ArrayList集合中使用 List.of() 集合的批量添加,就会报出Error:(18, 56) java: 找不到符号;软件包也正常导入了,什么问题求解答!!!
import java.util.ArrayList;
import java.util.List;
public class MyStream1 {
public static void main(String[] args) {
//集合的批量添加
ArrayList list1 = new ArrayList<>(List.of("张三丰","张无忌","张翠山","王二麻子","张良","谢广坤"));
//list.add("");
//遍历list1把张开头的元素添加到list2中
ArrayList<String> list2 = new ArrayList<>();
for (String s : list1) {
if (s.startsWith("张")) {
list2.add(s);
}
}
//遍历list2集合,把其中长度为3的元素,再添加到list3中
ArrayList<String> list3 = new ArrayList<>();
for (String s : list2) {
if (s.length() == 3){
list3.add(s);
}
}
for (String s : list3) {
System.out.println(s);
}
}
}`
用Arrays.asList方法,如下:
String arr[] = {"张三丰","张无忌","张翠山","王二麻子","张良","谢广坤"};
ArrayList list1 = new ArrayList<>();
list1.addAll(Arrays.asList(arr));
ArrayList list1 = new ArrayList<>(List.of("张三丰","张无忌","张翠山","王二麻子","张良","谢广坤"));
改为:
ArrayList<String> list1 = new ArrayList<>();
Collections.addAll(list1, "张三丰","张无忌","张翠山","王二麻子","张良","谢广坤");
List.of()
没有这样的方法
List.of是java9开始才有的方法,如果你安装的jdk是jdk8或者以下是没有这个方法的,所有报错了
我也是报错啊,而且我用的也是jdk11,都搞得我emo了,求博主解惑???
Map<String, Object> succData = Map.of(
"name","lipeng",
"university","sicnu"
);