到底哪错了

import java.util.*;
public class Am {//主程序
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        //System.out.println("--请定义人数--");
        Student[] stuArr=new Student[2];
        Admin adminStu=new Admin();
        
            System.out.println("--你要执行的功能:--");
            System.out.println("10:添加一个学生");
            System.out.println("11:查找一个学生");
            System.out.println("12:根据编号更新学生的基本信息");
            System.out.println("13:根据编号删除学生--");
            System.out.println("14:根据编号输入学生的各门成绩");
            System.out.println("15:根据某门成绩进行排序");
            System.out.println("16:根据总分进行排序");
            System.out.println("99:退出系统");
            
            if (in.nextInt()==10){
                System.out.println("请输入姓名");
                String name = in.next();
                System.out.println("请输入年龄");
                int age = in.nextInt();
                adminStu.creat("li",13,stuArr);
                }
            for (int i=0; i<stuArr.length; i++){
                if (stuArr[i]!=null){
                System.out.println(stuArr[i]);
            }
                }
            
}
}
  class Admin{//添加学生
      public void creat (String name,int age,Student[] arr){
          Student stu = new Student();
          stu.setName(name);
          stu.setAge(age);
          int i= this.setIndex(arr);   
          if (i==99999){
              System.out.println("人数已满，不可再添加");
              }
          else{
          arr[i] = stu;
          }
       int setIndex(Student[] arr){
          for (int i=0; i<arr.length; i++){
              if(arr[i] == null){
                  return i;
                  }
              }
         
          }
          return 99999;
      
      
      }
  }