Merge pull request #715 from Measuring/master

English - Scala - Changes to pattern matching, string interpolation and file writing

1 files changed, 30 insertions, 12 deletions

diff --git a/scala.html.markdown b/scala.html.markdown
index 432933c2..6b398b4b 100644
--- a/scala.html.markdown
+++ b/scala.html.markdown
@@ -299,7 +299,6 @@ Person("George", "1234") == Person("Kate", "1236")
 
 
 
-
 // Pattern matching
 
 val me = Person("George", "1234")
@@ -322,15 +321,21 @@ kate match { case Person("Kate", _) => "Girl"; case Person("George", _) => "Boy"
 
 
 // Regular expressions
-
 val email = "(.*)@(.*)".r  // Invoking r on String makes it a Regex
-
-val email(user, domain) = "henry@zkpr.com"
-
-"mrbean@pyahoo.com" match {
-  case email(name, domain) => "I know your name, " + name
+val serialKey = """(\d{5})-(\d{5})-(\d{5})-(\d{5})""".r // Using verbatim (multiline) syntax
+
+val matcher = (value: String) => {
+  println(value match {
+	case email(name, domain) => s"It was an email: $name"
+	case serialKey(p1, p2, p3, p4) => s"Serial key: $p1, $p2, $p3, $p4"
+	case _ => s"No match on '$value'" // default if no match found
+  })
 }
 
+matcher("mrbean@pyahoo.com") // => "It was an email: mrbean"
+matcher("nope..") // => "No match on 'nope..'"
+matcher("52917") // => "No match on '52917'"
+matcher("52752-16432-22178-47917") // => "Serial key: 52752, 16432, 22178, 47917"
 
 
 // Strings
@@ -347,17 +352,27 @@ println("ABCDEF".length)
 println("ABCDEF".substring(2, 6))
 println("ABCDEF".replace("C", "3"))
 
+// String interpolation
 val n = 45
-println(s"We have $n apples")
+println(s"We have $n apples") // => "We have 45 apples"
 
+// Expressions inside interpolated strings are also possible
 val a = Array(11, 9, 6)
-println(s"My second daughter is ${a(2-1)} years old")
+println(s"My second daughter is ${a(0) - a(2)} years old.") // => "My second daughter is 5 years old."
+println(s"We have double the amount of ${n / 2.0} in apples.") // => "We have double the amount of 22.5 in apples."
+println(s"Power of 2: ${math.pow(2, 2)}") // => "Power of 2: 4"
+
+// Formatting with interpolated strings (note the prefixed f)
+println(f"Power of 5: ${math.pow(5, 2)}%1.0f") // "Power of 5: 25"
+println(f"Square root of 122: ${math.sqrt(122)}%1.4f") // "Square root of 122"
+
+// Ignoring special characters.
+println(raw"New line feed: \n. Carriage return: \r.") // => "New line feed: \n. Carriage return: \r."
 
 // Some characters need to be 'escaped', e.g. a double quote inside a string:
-val a = "They stood outside the \"Rose and Crown\""
+val a = "They stood outside the \"Rose and Crown\"" // => "They stood outside the "Rose and Crown""
 
 // Triple double-quotes let strings span multiple rows and contain quotes
-
 val html = """<form id="daform">
                 <p>Press belo', Joe</p>
              |  <input type="submit">
@@ -403,7 +418,10 @@ for(line <- Source.fromFile("myfile.txt").getLines())
   println(line)
 
 // To write a file use Java's PrintWriter
-
+val writer = new PrintWriter("myfile.txt")
+writer.write("Writing line for line" + util.Properties.lineSeparator)
+writer.write("Another line here" + util.Properties.lineSeparator)
+writer.close()
 
 ```