写一个学生类，包括学号、姓名、年龄属性和一个构造方法,toString方法。2)主方法种键盘输入信息创建n个学生对象,将学生对象存放在集合中,按照年龄的高低排序输出. 要求: 1) 如果年龄不是整数,则抛出输入错误异常; 2)如果年龄小于3，抛出年龄低异常；如果年龄大于35，则抛出年龄高异常；3) 如果姓名或学号为空，则抛出空异常。编写测试程序。编写自定义异常类，包括空异常类、年龄低异常类和年龄高异常类。

好的，下面是代码实现：

import java.util.*;

class Student {
    private String id;
    private String name;
    private int age;

    public Student(String id, String name, int age) throws Exception {
        if (id == null || name == null || id.equals("") || name.equals("")) {
            throw new EmptyException();
        }
        if (age < 3) {
            throw new AgeLowException();
        }
        if (age > 35) {
            throw new AgeHighException();
        }
        if (age != (int) age) {
            throw new InputErrorException();
        }
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String toString() {
        return "学号：" + id + "，姓名：" + name + "，年龄：" + age;
    }

    public int getAge() {
        return age;
    }
}

class AgeLowException extends Exception {
    public AgeLowException() {
        super("年龄低异常");
    }
}

class AgeHighException extends Exception {
    public AgeHighException() {
        super("年龄高异常");
    }
}

class InputErrorException extends Exception {
    public InputErrorException() {
        super("输入错误异常");
    }
}

class EmptyException extends Exception {
    public EmptyException() {
        super("空异常");
    }
}

public class Test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入学生个数：");
        int n = scanner.nextInt();
        List<Student> students = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            try {
                System.out.println("请输入第" + (i + 1) + "个学生的信息：");
                System.out.print("学号：");
                String id = scanner.next();
                System.out.print("姓名：");
                String name = scanner.next();
                System.out.print("年龄：");
                int age = scanner.nextInt();
                Student student = new Student(id, name, age);
                students.add(student);
            } catch (InputErrorException | AgeLowException | AgeHighException | EmptyException e) {
                System.out.println(e.getMessage());
                i--;
            } catch (Exception e) {
                System.out.println("未知异常");
                i--;
            }
        }
        Collections.sort(students, new Comparator<Student>() {
            @Override
            public int compare(Student s1, Student s2) {
                return s2.getAge() - s1.getAge();
            }
        });
        System.out.println("按照年龄排序输出：");
        for (Student student : students) {
            System.out.println(student);
        }
    }
}

运行程序，输入学生个数和每个学生的信息，程序会按照学生年龄的高低排序输出，如果输入有误则会抛出相应的异常。