java-有理数类的设计

1.RationalNumber类的代码

package RationalNumber;

public class RationalNumber {
	private int numerator ;
	private int denominator ;
	
	public RationalNumber(int numerator,int denominator) {
		this.numerator = numerator;
		this.denominator = denominator;
		if(this.denominator==0) { //分母为0强制退出；
			throw new IllegalArgumentException("分母不可为0！");
		}
	}
	public int getNumberator() { //获取分子
		return this.numerator;
	}
	public int getDenominator() { //获取分母
		return this.denominator;
	}
	public int gcd() { //约分
		int t,m,n;
		m=this.denominator;
		n=this.numerator;
		if(n == 0)
		{
			return 0;
		}
		while(m % n != 0) {
			t=n;
			n=m%n;
			m=t;
		}
		this.denominator /= n;
		this.numerator /= n;
		return n;
	}
	public RationalNumber add(RationalNumber num) {  //加法
		int numerator,denominator;
		denominator=num.denominator*this.denominator;
		numerator=num.denominator*this.numerator+num.numerator*this.denominator;
		RationalNumber sum = new RationalNumber(numerator,denominator);
		sum.gcd();
		
		return sum;
	}
	public RationalNumber subtraction(RationalNumber num) {  //减法
		int numerator,denominator;
		
		
		denominator = num.denominator*this.denominator;
		numerator = this.numerator*num.denominator-num.numerator*this.denominator;
		RationalNumber difference = new RationalNumber(numerator,denominator);
		difference.gcd();
		
		return difference;
	}
	public RationalNumber multiply(RationalNumber num) {  //乘法
		
		
		int numerator=this.numerator*num.numerator;
		int denominator=this.denominator*num.denominator;
		RationalNumber product = new RationalNumber(numerator,denominator);
		product.gcd();
		
		return product;
	}
	public RationalNumber division(RationalNumber num) {  //除法
		if(num.numerator!=0)
		{
			int denominator = this.denominator * num.numerator;
			int numerator = this.numerator * num.denominator;
			RationalNumber quotient = new RationalNumber(numerator,denominator);
			quotient.gcd();
			return quotient;
		}
		else
		{
			throw new IllegalArgumentException("除数不可为0！");
		}
		
	}
	
	public boolean equals(RationalNumber num) {  //判断两个有理数是否相等；
        RationalNumber temp1 = new RationalNumber(this.numerator,this.denominator);
        RationalNumber temp2 = new RationalNumber(num.numerator,num.denominator);
		temp1.gcd();
		temp2.gcd();
		if(temp1.denominator==temp2.denominator && temp1.numerator==temp2.numerator) {
			return true;
		}
		else {
			return false;
		}
	}
	public double doubleValue() {  //转换为double型；
		return (double)this.numerator/this.denominator;
	}
	public int intValue() {   //取整数部分；
		return this.numerator/this.denominator;
	}
	public String toString() {  //得到该有理数的字符串形式
		
		return this.numerator+"/"+this.denominator;
	}
	public RationalNumber abs(){  //绝对值
		RationalNumber result = new RationalNumber(0,1);
		if(this.denominator<0) {
			result.denominator = -this.denominator;
		}
		else {
			result.denominator = this.denominator;
		}
		if(this.denominator<0) {
			result.numerator = -this.numerator;
		}
		else
		{
			result.numerator = this.numerator;
		}
		return result;
	}
}

2.1测试代码

package text;

import RationalNumber.RationalNumber;

public class text{
	public static void main(String [] args) {
		RationalNumber a = new RationalNumber (2,8);
		RationalNumber b = new RationalNumber (1,4);
		RationalNumber c = new RationalNumber (0,5);
		RationalNumber d = new RationalNumber (-1,3);
		
		System.out.println("获取a的分子分母："+a.getNumberator()+"/"+a.getDenominator());
		System.out.println("获取b的分子分母："+b.getNumberator()+"/"+b.getDenominator());
		System.out.println("获取c的分子分母："+c.getNumberator()+"/"+c.getDenominator());
		System.out.println("获取d的分子分母："+d.getNumberator()+"/"+d.getDenominator());
		System.out.println("a的绝对值："+a.abs().toString());
		System.out.println("d的绝对值："+d.abs().toString());
		System.out.println("a的值:"+a.doubleValue());
		System.out.println("a+b = "+a.add(b).toString());
		System.out.println("a-b = "+a.subtraction(b).toString());
		System.out.println("c/d = "+c.division(d).toString());
		System.out.println("c*d = "+c.multiply(d).toString());
		System.out.println("a和b是否相等："+b.equals(a));
		System.out.println("c和d是否相等："+c.equals(d));
		
		System.out.println("d/c = "+d.division(c).toString());
		RationalNumber r = new RationalNumber (1,0);//分母为0；
		
		System.out.println("r的值："+r.doubleValue());
	}
}

2.2测试结果

3.尝试描述怎么与c语言的有理数代码相比较,为什么你设计的类更加面向对象?

在c语言的有理数代码中，其中设置的函数都是为了完成某个步骤，在解决某个问题时，这些函数都是解决该问题中的一个步骤；在java设计的类中，是根据有理数的特性设计出其方法，是依托于有理数这一类的对象，所有的对象都具有相同的属性方法，且可随时抽取其中的属性和方法进行编程。而c语言中，是设计了每个解决步骤，然后再利用每个变量进行传参套用。

4.尝试从代码复用的角度来描述你设计的有理数类。从几个方面讨论。

4.1别人如何复用你的代码?

别人如何复用你的代码：将自己的代码打包发给别人，然后使用import导入有理数的包；

4.2别人的代码是否依赖你的有理数类的属性?当你的有理数类的属性修改时,是否会影响他人调用你有理数类的代码?

别人的代码不会依赖我有理数的属性，当我的有理数类属性修改时，不会影响到他人调用我有理数的代码，因为我属性的修饰符都为private；

4.3有理数类的public方法是否设置合适?为什么有的方法设置为private?

public使得用户在其他包中的类可以直接调用该方法，对于执行某些基础操作的方法来说，直接定义为public可以尽快的完成程序功能。如果是稍微比较复杂的操作，为了隐藏其中的细节保护其隐私，可以设置成private来进行封装。