清单 2. RunRational
class Rational(n:Int, d:Int)
{
// ... as before
}
object RunRational extends Application
{
val r1 = new Rational(1, 3)
val r2 = new Rational(2, 5)
val r3 = r1 - r2
val r4 = r1 + r2
Console.println("r1 = " + r1)
Console.println("r2 = " + r2)
Console.println("r3 = r1 - r2 = " + r3)
Console.println("r4 = r1 + r2 = " + r4)
}