20165103结对编程练习_四则运算（第二周）

import java.util.Random;
public class Fraction {
    private int numerator, denominator;  //定义分母、分子

    public  Fraction (int numer, int denom)
    {

        if(denom == 0 )        //分子为0
            denom = 1;
        if (denom < 0)           //若分母小于0，则取分母为正值，分子为负值
        {
            numer = numer * -1;
            denom = denom * -1;
        }
        numerator = numer;
        denominator = denom;

        reduce();
    }

    public int getNumerator()
    {
        return numerator;
    }

    public int getDenominator()
    {
        return denominator;
    }


    public Fraction add(Fraction op2)          //实现真分数加法运算
    {
        int commonDenominator = denominator * op2.getDenominator();   //两随机数a1、a2的分母相乘，进行通分
        int numerator1 = numerator * op2.getDenominator();            //a1的分子=a1的分子与a2的分母相乘
        int numerator2 = op2.getNumerator() * denominator;           //a2的分子=a2的分子与a1的分母相乘
        int sum = numerator1 + numerator2;                            //将通分过后的两个随机数相加
        System.out.print("("+this.toString()+")" + " + " + "("+op2.toString()+")" + "=");
        return new Fraction (sum, commonDenominator);
    }

    public Fraction subtract(Fraction op2)           //实现真分数减法运算
    {
        int commonDenominator = denominator * op2.getDenominator();
        int numerator1 = numerator * op2.getDenominator();
        int numerator2 = op2.getNumerator() * denominator;
        int difference = numerator1 - numerator2;
        System.out.print("("+this.toString()+")" + " - " + "("+op2.toString()+")" + "=");
        return new Fraction(difference,commonDenominator);
    }

    public Fraction multiply (Fraction op2)              //实现真分数乘法运算
    {
        int numer = numerator * op2.getNumerator();
        int denom = denominator * op2.getDenominator();
        System.out.print("("+this.toString()+")" + " * " + "("+op2.toString()+")" + "=");
        return new Fraction (numer, denom);
    }

    public Fraction divide (Fraction op2)              //实现真分数除法运算
    {

        int numer = numerator * op2.getDenominator();
        int denom = denominator * op2.getNumerator();
        System.out.print("("+this.toString()+")" + " / " + "("+op2.toString()+")" + "=");
        return new Fraction (numer, denom);
    }

    public String toString()      //输出格式及限定
    {
        String result;

        if (numerator == 0)               //分子为0，结果为0
            result = "0";
        else
        if(denominator == 0)              //分母不能为0
            return "错误！分母不能为0";
        else
        if (denominator == 1)             //分母为1，结果取分子值
            result = numerator + "";

        else
            result = numerator + "/" + denominator;  //按分数形式输出结果

        return result;
    }

    private void reduce()
    {
        if (numerator != 0)
        {
            int common = gcd (Math.abs(numerator), denominator);    //取分子分母最大公因子

            numerator = numerator / common;                        //约分
            denominator = denominator / common;
        }
    }


    private int gcd (int num1, int num2)                      //计算最大公因子
    {
        if(num2==0)
            return num1;
        else
            return gcd(num2,num1%num2);

    }
    public static Fraction obj(){                               //生成随机数
        Random ran = new Random();
        return new Fraction(ran.nextInt(100),ran.nextInt(100));
    }
}