取出list对象中的某一属性值
public class Store implements Serializable {
private Integer id;
private String userName;
private String phone;
}
public static void main(string args[]){
List<Store> users=new ArrayList<>();
users.add(new Store(1,"张三","18399990000"));
users.add(new Store(2,"王五","18399990023"));
users.add(new Store(3,"里斯","18399990005"));
List<String> courseIds= users.stream().map(Store::getUserName).collect(Collectors.toList());
}```