有理数类的设计

有理数类的设计

一、有理数类的代码

class Rational{
	private int numerator;//分子
	private int denominator;//分母
	public int getNumerator() {//获取分子
		return numerator;
	}
	public void setNumerator(int numerator) {
		this.numerator = numerator;
	}
	public long getDenominator() {//获取分母
		return denominator;
	}
	public void setDenominator(int denominator) {
		this.denominator = denominator;
	}
	public Rational() {
		super();
		this.numerator = 0;
		this.denominator = 1;
	}
	public Rational(int numerator, int denominator) {//构造函数
		super();
		int gcd = gcd(numerator,denominator);
		this.numerator = numerator/gcd;
		this.denominator = denominator/gcd;
	}
	private int gcd(int n, int d) {//辗转相除法
		int s1 = Math.abs(n);
		int s2 = Math.abs(d);
		int remander = s1%s2;
		while(remander!= 0) {
			s1 = s2;
			s2 = remander;
			remander = s1%s2;
		}
		return s2;
	}
	public Rational add(Rational secondRational) {//加法
		int n = numerator*secondRational.getDenominator()+denominator*secondRational.getNumerator();
		int d = denominator*secondRational.getDenominator();
		System.out.println(n+" "+d);
		return new Rational(n,d);
	}
	public Rational subtract(Rational secondRational) {//减法
		int n = numerator*secondRational.getDenominator()-denominator*secondRational.getNumerator();
		int d = denominator*secondRational.getDenominator();
	}
	public Rational multiply(Rational secondRational) {//乘法
		int n = numerator*secondRational.getNumerator();
		int d = denominator*secondRational.getDenominator();
		return new Rational(n,d);
	}
	public Rational divide(Rational secondRational) {//除法
		int n = numerator*secondRational.getDenominator();
		int d = denominator*secondRational.getNumerator();
		return new Rational(n,d);
	}
	public String toString() {//转化为字符串类型
		if(denominator == 1) {
			return numerator+"";
		}
		else {
			return numerator+"/"+denominator;
		}
	}
}

二、测试代码

public class testz{
	public static void main(String[] args) {
		Rational r1 = new Rational(2,1);
		Rational r2 = new Rational(2,3);
		System.out.println(r1.toString()+"+"+r2.toString()+"="+(r1.add(r2)).toString());
		System.out.println(r1.toString()+"-"+r2.toString()+"="+(r1.subtract(r2)).toString());
		System.out.println(r1.toString()+"*"+r2.toString()+"="+(r1.multiply(r2)).toString());
		System.out.println(r1.toString()+"/"+r2.toString()+"="+(r1.divide(r2)).toString());
	}
}

三、讨论

1、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？

c语言会更多考虑面向过程，用什么函数来实现它，过程要怎么样；类中很多已经规定好了，直接调用就行了，更多会思考如何优化对象。

2、别人如何复用你的代码？

导入有理数类的属性。

3、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?

依赖，有影响。

4、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?

publish方法可以被任何成员访问，private方法仅限自己访问。本次设计中private隐藏的是两个数据（long numerator，long denominator）。