1.有理數類的程式碼

import java.util.Scanner;

public class Rational {

	private int numberator=0;
	private int denominator=1;
	

	public Rational() {
		this(0,1);
	}
	
	public Rational(int numberator,int denominator) {     
    	
		if (numberator == 0) {
			this.numberator = numberator;
			this.denominator = denominator;
		} 
		else {
			int com = maxCom(Math.abs(numberator), Math.abs(denominator));//求最大公約數
			if (denominator < 0) {
				numberator = -numberator;
				denominator = -denominator;
			}
			this.numberator = numberator / com;
			this.denominator = denominator / com;
		}
    }
	
	private int maxCom(int a, int b) { // 求最大公約數
		if (a < b) {
			int c = a;
			a = b;
			b = c;
		}
		int r = 0;
		try {
			r = a % b;

		} catch (Exception e) {
			System.out.println(e.getMessage());
		} // 分母為零時異常處理
		while (r != 0) {
			a = b;
			b = r;
			r = a % b;
		}

		return b;
	}
	
	public Rational add(int numberator,int denominator) {
		int d = denominator;
		denominator = this.denominator * denominator;
		numberator = this.numberator * d + numberator * this.denominator;
		
		return new Rational(numberator, denominator);

	}
	public Rational sub(int numberator, int denominator) {// 減
		int d = denominator;
		denominator = this.denominator * denominator;
		numberator = this.numberator * d - numberator * this.denominator;
		
		return new Rational(numberator, denominator);
	}

	public Rational mul(int numberator, int denominator) {// 乘
		
		denominator = this.denominator * denominator;
		numberator = this.numberator * numberator;

		return new Rational(numberator, denominator);
	}

	public FractionalNumber div(int numberator, int denominator) {// 除
		int d = denominator;
		denominator = this.denominator * numberator;
		numberator = this.numberator * d;

		return new FractionalNumber(numberator, denominator);
	}
	
	public String toString() {
		return numberator + "/" + denominator;
	}
 

2.測試程式碼

public static void main (String[] args) {
		{
			System.out.println("請輸入要計算的表示式：");
			Scanner sc=new Scanner(System.in);
			String str=sc.next();
			int a=Integer.parseInt(str.charAt(0)+"");//分子
			int b=Integer.parseInt(str.charAt(2)+"");//分母
			int c=Integer.parseInt(str.charAt(4)+"");
			int d=Integer.parseInt(str.charAt(6)+"");
			
			Rational num=new Rational(a,b);
			
			switch(str.charAt(3)) {
			case'+':System.out.println("加法");
				System.out.println(num.add(c,d).toString());
			//break;測試程式碼
			case'-':System.out.println("減法");
				System.out.println(num.sub(c,d).toString());
			//break;
			case'*':System.out.println("乘法");
				System.out.println(num.mul(c,d).toString());
			//break;
			case'/':System.out.println("除法");
				System.out.println(num.div(c,d).toString());
			//break;
			}
}}
}
 

3.嘗試描述怎麼與c語言的有理數程式碼相比較,為什麼你設計的類更加面向物件?

c語言的有理數程式碼，我會傾向於從過程考慮，考慮要寫怎樣的函式來用它，而不是考慮它應該會有怎樣的方法.

4.嘗試從程式碼複用的角度來描述你設計的有理數類。從幾個方面討論。

a.別人如何複用你的程式碼?
匯入我書寫的類的包，就可以使用我寫的類和方法

b.別人的程式碼是否依賴你的有理數類的屬性?當你的有理數類的屬性修改時,是否會影響他人呼叫你有理數類的程式碼?
依賴，我的有理數類的為private，所以不會影響他人呼叫我的有理數程式碼

c.有理數類的public方法是否設定合適?為什麼有的方法設定為private?
適合