奇奇怪怪的知识

package js_ecu_app;

import java.util.*;
import java.util.stream.Collectors;


public class test3 {
    public static void main(String[] args) {

//        HashSet<String> set = new HashSet<>();
//        String num = "12,12,14";
//
//        String[] split = num.split(",");
//        for (String s : split) {
//            set.add(s);
//        }
//        System.out.println(set.toString());

        List<Map<String,Object>> list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Map<String,Object> map = new HashMap<>();
            map.put("city","12,13,14,15"+i);
            map.put("phone","1885544288"+i);
            list.add(map);
        }
        Map<String,Object> map1 = new HashMap<>();
        //放入空值
        map1.put("city","");
        map1.put("phone","");
        list.add(map1);
        System.out.println(list.toString());
        System.out.println("******************************************");
        List<Object> city = list.stream().map(map -> (!"".equals(map.get("city")))?map.get("city"):"null").collect(Collectors.toList());
        List<Object> phone = list.stream().map(map -> (!"".equals(map.get("phone")))?map.get("phone"):"null").collect(Collectors.toList());
        System.out.println(city.toString());
        System.out.println(phone.toString());
    }
}