java中如何制定自定义异常

 package gys;

 public class ExpetionTest {
     public static void main(String[] args) {
         NumberCheck n=new NumberCheck();
         try {
             System.out.println(n.division(1,-3));
         } catch (ZerpSubException e) {
             System.out.println(e.getMessage());
         } catch (ZeroException e) {
             System.out.println(e.getMessage());
         }
         catch(Exception ex){
             System.out.println(ex.getMessage());
         }
     }
 }
 class ZeroException extends Exception{
     public ZeroException(String msg){
         super(msg);
     }
 }
 class ZerpSubException extends Exception{
     public ZerpSubException(String msg){
         super(msg);
     }
 }
 class NumberCheck{
     //除法
     public int division(int x,int y) throws ZeroException,ZerpSubException{
         if(y<0){
             throw new ZerpSubException("除数不能为负数");
         }
         if(y==0){
             throw new ZeroException("除数不能为0");
         }
         int m=x/y;
         return m;
     }
 }