list中加不进去

Question

  for(i=0;i<count;i++){

    System.out.print("请输入姓名：");

sj.setName(sc.next());

System.out.print("请输入年龄：");

sj.setAge(sc.nextInt());

System.out.print("请输入成绩：");

sj.setGrade(sc.nextDouble());

        list.add(sj);  

    }

      for (int j = 0; j < list.size(); j++) {  

      System.out.println(list.get(j));

      }  

Answer 1

list<sj> list=new arrayList<sj>();

Answer 2

要先有对象才能add进去

Answer 3

for循环中得先定义对象实例 ，你没有定义  Student s= new Student();