分数计算

import java.util.Scanner;
public class test{
    public static void main(String args[]){
        Rational a=new Rational(4,5);
        Rational b=new Rational(3,2);
        Rational c=a.chu(b);
        c.show();
    }
}

class Rational{
    int fenzi=1;
    int fenmu=1;
    int f(int a,int b){//公约数
        if(b>a){
            int c=a;
            a=b;
            b=c;
        }
//        System.out.println(a);
        int c=a%b;
        for(;c!=0;c=a%b){
            a=b;
            b=c;
        }
        return b;
        }
    Rational(int a,int b){
        int c=f(Math.abs(a),Math.abs(b));
        fenzi=a/c;
        fenmu=b/c;
        System.out.println(c);
    }
    Rational jia(Rational r){
        int a=fenzi*r.fenmu+r.fenzi*fenmu;
        int b=fenmu*r.fenmu;
//        System.out.println(b);
        Rational c=new Rational(a,b);
        return c;
    }
    Rational jian(Rational r){
        int a=fenzi*r.fenmu-r.fenzi*fenmu;
        int b=fenmu*r.fenmu;
//        System.out.println(b);
        Rational c=new Rational(a,b);
        return c;
    }
    Rational cheng(Rational r){
        int a=fenzi*r.fenzi;
        int b=fenmu*r.fenmu;
        Rational c=new Rational(a,b);
        return c;
    }
    Rational chu(Rational r){
        int a=fenzi*r.fenmu;
        int b=fenmu*r.fenzi;
        Rational c=new Rational(a,b);
        return c;
    }
    void show(){
        System.out.println(fenzi+"/"+fenmu);
    }
}