scala for impatient exercise chapter 4 Maps and tuples

ex4.scala

/*
Set up a map of prices for a number of gizmos that you covet. Then produce
a second map with the same keys and the prices at a 10 percent discount.
*/

val gizmos = Map("Laptop" -> 100 ,"Mobile" -> 200)
val tenPec = for((g,p) <- gizmos) yield (g,p-p*0.1)

/*
Write a program that reads words from a file. Use a mutable map to count
how often each word appears.
*/

def countWords :Unit ={
 val in = new java.util.Scanner(new java.io.File("C:/text.txt")).useDelimiter("\\s")
 val map = new scala.collection.mutable.HashMap[String, Int]
 while(in.hasNext) {           
 val s = in.next()            
 map(s) = map.getOrElse(s,0)+1
 print(s +" ")
 }
 println()
 println(map)   

}

/*Repeat the preceding exercise with an immutable map.*/

def countWords :Unit ={
 val in = new java.util.Scanner(new java.io.File("C:/text.txt")).useDelimiter("\\s")
 var map = Map[String,Int]()
 while(in.hasNext) {           
 val s = in.next()            
 map = map + (s -> (map.getOrElse(s,0)+1))
 print(s +" ")
 }
 println()
 println(map)   

}


def countWordsSorted :Unit ={
 val in = new java.util.Scanner(new java.io.File("C:/text.txt")).useDelimiter("\\s")
 var map = scala.collection.immutable.SortedMap[String,Int]()
 while(in.hasNext) {           
 val s = in.next()            
 map = map + (s -> (map.getOrElse(s,0)+1))
 print(s +" ")
 }
 println()
 println(map)   

}


/*

Print a table of all Java properties, like this:
java.runtime.name | Java(TM) SE Runtime Environment
sun.boot.library.path | /home/apps/jdk1.6.0_21/jre/lib/i386
java.vm.version | 17.0-b16
java.vm.vendor | Sun Microsystems Inc.
java.vendor.url | http://java.sun.com/
path.separator | :
java.vm.name | Java HotSpot(TM) Server VM
You need to find the length of the longest key before you can print the table.
*/

val props: scala.collection.Map[String, String] = System.getProperties()
val keyToLength = for((k,v) <- props) yield (k -> k.length)
var max:(String,Int) = ("",Int.MinValue)
for((k,v) <- keyToLength) if(v > max._2) max = (k,v)
for((k,v) <- props) println(k+(" "*(maxLength+5-k.length)+"|"+v)) 

More concise code for the last one:

def printProperties() {
        val props = System.getProperties
        var max = props.keys().map(_.asInstanceOf[String].length()).max
        for ((k, v) <- props) println(k + " "*(max - k.length()) + " | " + v)
        
    }

Instead of using string multiplication and doing a (maxlength - keylength) to do the alignment right, String.format("%-", k) is readable. Of course, this is a non-Scala solution, but if there is a tool built for it (like how you used map and max to find the maxlength), why not?