//将List集合转换为数组 List<String> list= new ArrayList<String>(); list.add("李怡欣"); list.add("许文静"); list.add("小磊子"); String [] result = list.toArray(new String[list.size()]); for (int i = 0; i < result.length; i++) { System.out.println(result[i]); } //将...
"hello world 2");// 查询数据Strings1=list.get(0);// 查询List是否包含指定对象booleanisContain=list.contains(s1);// 查询列表的元素个数intsize=list.size();// 打印list内部元素:Stringres=list.toString();
var res = new ArrayList<User>(); for (User user : users) { if (user.age() > 30) { res.add(user); } } System.out.println(res); } enum Gender { MALE, FEMALE } record User(String name, int age, Gender gender) { } The program filter out all users that are older than thirty...
res.add(new ArrayList<>(list)):为深拷贝 import java.util.ArrayList;publicclassTest{publicstaticvoidmain(String[]args){ArrayList<Integer>list=newArrayList<Integer>();list.add(1);list.add(2);list.add(3);ArrayList<ArrayList<Integer>>res=newArrayList<ArrayList<Integer>>();ArrayList<ArrayList<Integer...
=newArrayList<>();// 插入数据list.add("hello world 1");// 在指定位置插入数据list.add(0,"hello world 2");// 查询数据Strings1=list.get(0);// 查询List是否包含指定对象booleanisContain=list.contains(s1);// 查询列表的元素个数intsize=list.size();// 打印list内部元素:Stringres=list....
List<int[]> res = new ArrayList<>(); for(int[] person : people){ res.add(person[1], person); } return res.toArray(new int[0][]); //List<int[]> 转 int[][] } } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. ...
关于数组变量嵌套写法:List<List<Integer>> res=new ArrayList<>(); 其实就是在List中存放List: 可以理解示例中的为向res中继续加list List<List<Integer>> res = new ArrayList<ArrayList<Integer>>(); List<Integer> list = new ArrayList<Integer>(); list.add(1); list.add(2);res.add(list); 全部...
List<String> list1=new ArrayList<String>(); list1.add("a1"); list1.add("a2"); list1.add("a3"); List<String> list2=new ArrayList<String>(); list2.add("b1"); list2.add("b2"); list2.add("b3"); redisTemplate.opsForList().leftPush("listkey1",list1); redisTemplate.opsForLis...
String m = "201,210-212,289,345-346";String[] strArr = m.split(",");List list = new ArrayList();for(int i=0;i<strArr.length;i++){ if(strArr[i].indexOf("-") != -1){ String[] tmpArr = strArr[i].split("-");for(int n = Integer.parseInt(tmpArr[0]);n...
itemList.add(resList.get(pre * subListLength + i)); } ret.add(itemList); } } returnret; } // 运行代码 publicstaticvoidmain(String[] args){ List<String> list = Lists.newArrayList; intsize =1099; for(inti =0; i < size; i++) { ...