OO设计-有理数类的设计

完整的有理数类的代码

package oo;

public class RationalNumber {
	private int numerator;//分子
	private int denominator;//分母
	public int GetNumerator() {
		return numerator;
	}
	
	public int GetDenominator() {
		return denominator;
	}
	
	private static int gcd(int x,int y) {
		if(x%y==0)
			return y;
		else
			return gcd(y, x%y);
	}
	
	public RationalNumber (int numerator,int denominator) {
		int gcd=gcd(numerator, denominator);
		this.numerator=((denominator>0)?1:-1)*numerator/gcd;
		this.denominator=Math.abs(denominator)/gcd;
	}
	
	public RationalNumber add(RationalNumber newRational) {
		int x=this.numerator*newRational.GetDenominator()+this.denominator*newRational.GetNumerator();
		int y=this.denominator*newRational.GetDenominator();
		return new RationalNumber(x,y);
	}    //加
	
	public RationalNumber subtract(RationalNumber newRational) {
		int x=this.numerator*newRational.GetDenominator()-this.denominator*newRational.GetNumerator();
		int y=this.denominator*newRational.GetDenominator();
		return new RationalNumber(x,y);
	}    //减
	
	public RationalNumber multiply(RationalNumber newRational) {
		int x=this.numerator*newRational.GetNumerator();
		int y=this.denominator*newRational.GetDenominator();
		return new RationalNumber(x,y);
	}    //乘
	
	public RationalNumber divide(RationalNumber newRational) {
		int x=this.numerator*newRational.GetDenominator();
		int y=this.denominator*newRational.GetNumerator();
		return new RationalNumber(x,y);
	}    //除
}

测试代码

package oo;

public class Main {

	public static void main(String[] args) {
		RationalNumber x=new RationalNumber(4,2);
		RationalNumber y=new RationalNumber(1,7);
        System.out.println("x="+x.toString());
        System.out.println("y="+y.toString());
        System.out.println("x+y="+x.add(y));
        System.out.println("x-y="+x.subtract(y));
        System.out.println("x*y="+x.multiply(y));
        System.out.println("x/y="+x.divide(y));

	}

}

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?

Java中设计的类更面向对象的原因是类提供了一种模板，可以根据相应的要求更简洁方便的创造更改对象。

讨论

1.别人如何复用你的代码?

导入自己编写的有理数包，从而调用类中的属性和方法

2.别人的代码是否依赖你的有理数类的内部属性?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?

不依赖，不会

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?

合适，提高代码的安全性。