diff options
| -rw-r--r-- | scala.html.markdown | 42 |
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() ``` |