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;
    }
}