Scala第一個Demo（大專案的一塊磚）
package com.leep.scala
/**
* 定義有理數類，並完成加減乘除運算
*/
class Rational (n:Int,d:Int){
require(d!=0) // 分母不為零
private val g=gcd(n.abs,d.abs) //最大公約數
val number = n/g
val denom = d/g
def this(n:Int) = this(n,1) //輔助構造器
def + (that: Rational) :Rational =
new Rational (number * that.denom+that.number * denom,
denom * that.denom
)
def + (i: Int): Rational =
new Rational(number + i*denom,denom)
def -(that:Rational) =
new Rational(
number * that.denom - that.number * denom,
denom * that.denom
)
def - (i:Int): Rational =
new Rational(number - i * denom, denom)
def * (that: Rational) : Rational =
new Rational (number * that.number, denom * that.denom)
def * (i: Int) : Rational =
new Rational (number * i,denom)
def / (that: Rational) :Rational =
new Rational (number * that.denom, denom * that.number)
def / (i : Int) : Rational =
new Rational(number, i * denom)
override def toString = number + "/" + denom //過載 toString 方法
/**
* 計算兩個數的最大公約數
* 用到遞迴
*/
private def gcd(a:Int,b:Int) : Int = {
if (b==0)
a
else
gcd(b,a%b)
}
}
/**
* 半身物件，這裡主要為測試用
*/
object Rational{
def main(args: Array[String]): Unit = {
val rl = new Rational(1,2);
println(rl)
val rs = rl+ new Rational(1);
println(rs)
}
}