scala_tutorial

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Scala val nums: Map[Int, Int] = Map() println( "Keys in colors : " + colors.keys ) println( "Values in colors : " + colors.values ) println( "Check if colors is empty : " + colors.isEmpty ) println( "Check if nums is empty : " + nums.isEmpty ) } } Save the above program in Demo.scala. The following commands are used to compile and execute this program. \>scalac Demo.scala \>scala Demo Output Keys in colors : Set(red, azure, peru) Values in colors : MapLike(#FF0000, #F0FFFF, #CD853F) Check if colors is empty : false Check if nums is empty : true Concatenating Maps You can use either ++ operator or Map.++() method to concatenate two or more Maps, but while adding Maps it will remove duplicate keys. Try the following example program to concatenate two Maps. object Demo { def main(args: Array[String]) { val colors1 = Map("red" -> "#FF0000", "azure" -> "#F0FFFF", "peru" -> "#CD853F") val colors2 = Map("blue" -> "#0033FF", "yellow" -> "#FFFF00", "red" -> "#FF0000") 124
Scala // use two or more Maps with ++ as operator var colors = colors1 ++ colors2 println( "colors1 ++ colors2 : " + colors ) // use two maps with ++ as method colors = colors1.++(colors2) println( "colors1.++(colors2)) : " + colors ) } } Save the above program in Demo.scala. The following commands are used to compile and execute this program. \>scalac Demo.scala \>scala Demo Output colors1 ++ colors2 : Map(blue -> #0033FF, azure -> #F0FFFF, peru -> #CD853F, yellow -> #FFFF00, red -> #FF0000) colors1.++(colors2)) : Map(blue -> #0033FF, azure -> #F0FFFF, peru -> #CD853F, yellow -> #FFFF00, red -> #FF0000) Print Keys and Values from a Map You can iterate through the keys and values of a Map using “foreach” loop. Here, we used method foreach associated with iterator to walk through the keys. Following is the example program. object Demo { def main(args: Array[String]) { val colors = Map("red" -> "#FF0000", "azure" -> "#F0FFFF", "peru" -> "#CD853F") 125
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Scala About the Tutorial Scala is a
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Scala 4. SCALA - DATA .............
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Scala Higher-Order Functions ......
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Scala Regular-Expression Examples .
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Scala Scala can Execute Java Code S
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Scala We assume that the readers of
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Scala Windows \>scala -version Scal
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Scala Welcome to Scala version 2.9.
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Scala $salary, 123abc, -salary Oper
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Scala Newline Characters Scala is a
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4. SCALA - DATA Scala Scala has all
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Scala "Hello,\nWorld!" "This string
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5. SCALA - VARIABLES Scala Variable
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Scala } Save the above program in D
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Methods Variables 6. SCALA - CLASSE
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Scala } Save the above program in D
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Scala \>scala Demo Output Point x l
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Scala Implicit classes may not be
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7. SCALA - ACCESS MODIFIERS Scala T
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Scala } Scope of Protection Access
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8. SCALA - OPERATORS Scala An opera
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Scala == (Equal) 1 Checks if the va
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Scala It is called Logical AND oper
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Scala Ex: (A & B) will give 12, whi
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Scala \>scala Demo Output: a & b =
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Scala Try the following example pro
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Scala c &= a = 0 c ^= a = 10 c |= a
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9. SCALA - IF ELSE STATEMENT Scala
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Scala if(Boolean_expression){ //Exe
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Scala }else if( x == 30 ){ println(
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10. SCALA - LOOP STATEMENTS Scala T
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Scala while(condition) { Conditiona
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Scala jumps back up to do, and the
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Scala object Demo { } def main(args
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Scala } } Save the above program in
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Scala Scala's for loop allows to fi
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Scala \>scalac Demo.scala \>scala D
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Scala object Demo { def main(args:
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Scala Output: Value of a: 1 Value o
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11. SCALA - FUNCTIONS Scala A funct
Page 82 and 83: Scala var sum:Int = 0 sum = a + b r
Page 84 and 85: Scala println("Arg value[" + i + "]
Page 86 and 87: Scala } Save the above program in D
Page 88 and 89: Scala logWithDateBound("message3" )
Page 90 and 91: Scala \>scala Demo Output Factorial
Page 92 and 93: Scala Currying Functions Currying t
Page 94 and 95: 12. SCALA - CLOSURES Scala A closur
Page 96 and 97: 13. SCALA - STRINGS Scala This chap
Page 98 and 99: Scala "My name is ".concat("Zara");
Page 100 and 101: Scala val name = “James” printl
Page 102 and 103: Scala b String Methods Following is
Page 104 and 105: Scala 27 28 29 30 31 32 33 34 35 36
Page 106 and 107: 14. SCALA - ARRAYS Scala Scala prov
Page 108 and 109: Scala } println("Total is " + total
Page 110 and 111: Scala Save the above program in Dem
Page 112 and 113: Scala print( " " + x ) } println()
Page 114 and 115: 15. SCALA - COLLECTIONS Scala Scala
Page 116 and 117: Scala val nums = Nil println( "Head
Page 120 and 121: Scala 1 2 3 4 5 6 7 8 9 10 11 12 13
Page 122 and 123: Scala 34 35 36 37 38 39 40 41 42 43
Page 126 and 127: Scala Find Common Values Insets You
Page 128 and 129: Scala 14 def diff(that: Set[A]): Se
Page 130 and 131: Scala 39 def sum: A Returns the sum
Page 134 and 135: Scala colors.keys.foreach{ i => pri
Page 136 and 137: Scala 5 def iterator: Iterator[(A,
Page 138 and 139: Scala 30 def min: (A, B) Finds the
Page 140 and 141: Scala You can use Tuple to write a
Page 142 and 143: Scala Concatenated String: (1,hello
Page 144 and 145: Scala } } Save the above program in
Page 146 and 147: Scala 2 def isEmpty: Boolean Return
Page 148 and 149: Scala number of words Find Min & Ma
Page 150 and 151: Scala 4 def ++[B >: A](that :=> Gen
Page 152 and 153: Scala 28 def max: A Finds the large
Page 154 and 155: 16. SCALA - TRAITS Scala A trait en
Page 156 and 157: Scala Value classes and Universal T
Page 158 and 159: 17. SCALA - PATTERN MATCHING Scala
Page 160 and 161: Scala val charlie = new Person("Cha
Page 162 and 163: 18. SCALA - REGULAR EXPRESSIONNS Sc
Page 166 and 167: Scala \\n Back-reference to capture
Page 168 and 169: Scala val pattern = new Regex("abl[
Page 170 and 171: Scala } } } } Save the above progra
Page 172 and 173: 20. SCALA - EXTRACTORS Scala An ext
Page 174 and 175: Scala def main(args: Array[String])
Page 176 and 177: Scala print("Please enter your inpu
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