Number formatting in Scala?

Question

I have a dynamically changing input reading from a file. The numbers are either Int or Double. Why does Scala prints .0 after every Double numbers? Is there a way for Scala to print it the same way it reads it

Example:

var x:Double = 1
println (x)             // This prints '1.0', I want it to print '1'
x = 1.0                 // This prints '1.0', which is good

I can't use Int because some of the input I get are Doubles. I can't use String or AnyVal because I perform some math operations.

Thank you,

Answer 1

Use printf:

printf("The value is %.0f", x)

For a description of the format string, see this page from the Java SE 6 API documentation.

Note that you can ofcourse also use the Java library from Scala, so other ways to format numbers from Java can also be used from Scala. You can for example use class java.text.DecimalFormat:

val df = new java.text.DecimalFormat("#####")
println(df.format(x))

Answer 2

var x:Double = 1
var y:Double = 1.0

print(x) // => 1.0
print(y) // => 1.0

If i understand you question you want scala to print x and y differently? The problem is that x and y are both a variable of the type Double and look the same.

Why do you explicitly define the type of the vars?

var x = 1 
var y= 1.0

print(x) // => 1
print(y) // => 1.0

Answer 3

Use type inference, rather than explicit typing.

scala> val xi = 1
xi: Int = 1

scala> val xd = 1.0
xd: Double = 1.0

scala> println(xi)
1

scala> println(xd)
1.0

Answer 4

scala> "%1.0f" format 1.0 res3: String = 1

If your input is either Int or Double, you can do it like this:

def fmt(v: Any): String = v match {
  case d : Double => "%1.0f" format d
  case i : Int => i.toString
  case _ => throw new IllegalArgumentException
}

Usage:

scala> fmt(1.0)
res6: String = 1

scala> fmt(1)
res7: String = 1

scala> fmt(1.0f)
java.lang.IllegalArgumentException
        at .fmt(<console>:7)
        at .<init>(<console>:6)
        at .<clinit>(<console>)
        at RequestResult$.<init>(<console>:4)
        at RequestResult$.<clinit>(<console>)
        at RequestResult$result(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.Dele...

Otherwise, you might use BigDecimals. They are slow, but they do come with the scale, so "1", "1.0" and "1.00" are all different:

scala> var x = BigDecimal("1.0")
x: BigDecimal = 1.0

scala> x = 1
x: BigDecimal = 1

scala> x = 1.0
x: BigDecimal = 1.0

scala> x = 1.000
x: BigDecimal = 1.0

scala> x = "1.000"
x: BigDecimal = 1.000