我需要使用特定对象的属性(位置)对对象(学生)列表进行分组,代码如下所示,
public class Grouping { /** * @param args the command line arguments */ public static void main(String[] args) { List<Student> studlist = new ArrayList<Student>(); studlist.add(new Student("1726", "John", "New York")); studlist.add(new Student("4321", "Max", "California")); studlist.add(new Student("2234", "Andrew", "Los Angeles")); studlist.add(new Student("5223", "Michael", "New York")); studlist.add(new Student("7765", "Sam", "California")); studlist.add(new Student("3442", "Mark", "New York")); //Code to group students by location /* Output should be Like below ID : 1726 Name : John Location : New York ID : 5223 Name : Michael Location : New York ID : 4321 Name : Max Location : California ID : 7765 Name : Sam Location : California */ for (Student student : studlist) { System.out.println("ID : "+student.stud_id+"\t"+"Name : "+student.stud_name+"\t"+"Location : "+student.stud_location); } } } class Student { String stud_id; String stud_name; String stud_location; Student(String sid, String sname, String slocation) { this.stud_id = sid; this.stud_name = sname; this.stud_location = slocation; } }
请给我建议一个干净的方法。
In Java 8:
Map<String, List<Student>> studlistGrouped = studlist.stream().collect(Collectors.groupingBy(w -> w.stud_location));