[Java] custom exception class

When a fraction, numerator or denominator is negative, an exception is thrown.

package itheima2;
import java.util.*;
public class Main {
    
    
    public static void main(String[] args) {
    
    
        Scanner scanner = new Scanner(System.in);
        int n,m;
        n = scanner.nextInt();
        m = scanner.nextInt();
        try{
    
    
            int t = ecm(n,m);
            System.out.println(t);
        }catch (ArithmeticException e){
    
    
            System.out.println(e.getMessage());
        }
    }
    public static int ecm(int n,int m) {
    
    
        try{
    
    
            if(n < 0 || m < 0){
    
    
                throw new EcmDef("分子或分母为负数了"); //当符合分子分母小于0时，主动抛出
            }

        }catch (EcmDef e){
    
     //抓住异常
            System.out.println(e.getMessage());
        }
        return n / m;

    }

}
class EcmDef extends Exception{
    
     // 手写异常类要继承
    public EcmDef() {
    
    
    }

    public EcmDef(String message) {
    
    
        super(message);
    }
}