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- [ADD] PrintWriter example from Java
- [CHANGE] Extended regex matching with more examples with switch / case - [CHANGE] String interpolation with formatting and expressions explained.
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@ -299,7 +299,6 @@ Person("George", "1234") == Person("Kate", "1236")
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// Pattern matching
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val me = Person("George", "1234")
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@ -322,15 +321,22 @@ kate match { case Person("Kate", _) => "Girl"; case Person("George", _) => "Boy"
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// Regular expressions
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val email = "(.*)@(.*)".r // Invoking r on String makes it a Regex
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val serialKey = """(\d{5})-(\d{5})-(\d{5})-(\d{5})""".r // Using multiline string syntax
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val email(user, domain) = "henry@zkpr.com"
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"mrbean@pyahoo.com" match {
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case email(name, domain) => "I know your name, " + name
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val matcher = (value: String) => {
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println(value match {
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case email(name, domain) => s"It was an email: $name"
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case serialKey(p1, p2, p3, p4) => s"Serial key: $p1, $p2, $p3, $p4"
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case _ => s"No match on '$value'" // default if no match found
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})
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}
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matcher("mrbean@pyahoo.com")
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matcher("nope..")
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matcher("52917")
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matcher("52752-16432-22178-47917")
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// Strings
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@ -347,17 +353,27 @@ println("ABCDEF".length)
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println("ABCDEF".substring(2, 6))
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println("ABCDEF".replace("C", "3"))
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// String interpolation
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val n = 45
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println(s"We have $n apples")
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// Expressions inside interpolated strings are also possible
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val a = Array(11, 9, 6)
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println(s"My second daughter is ${a(2-1)} years old")
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println(s"My second daughter is ${a(0) - a(2)} years old")
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println(s"We have double the amount of ${n / 2.0} in apples.")
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println(s"Power of 2: ${math.pow(2, 2)}") // Power of 2: 4.0
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// Formatting with interpolated strings (note the prefixed f)
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println(f"Power of 5: ${math.pow(5, 2)}%1.0f") // Power of 5: 25
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println(f"Square root of 122: ${math.sqrt(122)}%1.4f") // Square root of 122
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// Ignoring special characters.
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println(raw"New line feed: \n. Carriage return: \r.")
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// Some characters need to be 'escaped', e.g. a double quote inside a string:
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val a = "They stood outside the \"Rose and Crown\""
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// Triple double-quotes let strings span multiple rows and contain quotes
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val html = """<form id="daform">
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<p>Press belo', Joe</p>
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@ -403,7 +419,10 @@ for(line <- Source.fromFile("myfile.txt").getLines())
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println(line)
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// To write a file use Java's PrintWriter
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val writer = new PrintWriter("myfile.txt")
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writer.write("Writing line for line" + util.Properties.lineSeparator)
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writer.write("Another line here" + util.Properties.lineSeparator)
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writer.close()
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```
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