public?class?Course?{ public?String?id; public?String?name; public?Course(String?id,String?name){ this.id=id; this.name=name; } }import?java.util.HashSet; import?java.util.Set; public?class?Student?{ public?String?id; public?String?name; public?Set?courses; public?Student(String?id,String?name){ this.id=id; this.name=name; this.courses=new?HashSet(); } }import?java.util.ArrayList; import?java.util.List; public?class?TestAdd?{ public?List<Course>?courseAll; public?TestAdd(){ this.courseAll=new?ArrayList(); } public?void?Add(){ Course?cr1=new?Course("1","數據結構"); courseAll.add(cr1); Course?cr2=new?Course("2","C語言"); courseAll.add(1,?cr2); courseAll.add(new?Course("3","數學")); courseAll.add(new?Course("4","語文")); } public?void?use(){ TestAdd?it=new?TestAdd(); it.Add(); for(Course?cr:it.courseAll){ System.out.println("id:?"+cr.id+" name:?"+cr.name); } } }public?class?Main?{ public?static?void?main(String[]?args)?{ TestAdd?add=new?TestAdd(); add.Add(); add.use(); } }