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CHAPTER 3 Scala Basic Syntax If you have good understanding on Java, then it will be very easy for you to learn Scala. The biggest syntactic difference between Scala and Java is that the ; line end character is optional. When we consider a Scala program it can be defined as a collection of objects that communicate via invoking each others methods. Let us now briefly look into what do class, object, methods and instant variables mean. Object - Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behaviors - wagging, barking, eating. An object is an instance of a class. Class - A class can be defined as a template/blueprint that describes the behaviors/states that object of its type support. Methods - A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed. Fields - Each object has its unique set of instant variables, which are called fields. An object's state is created by the values assigned to these fields. First Scala Program: INTERACTIVE MODE PROGRAMMING: Invoking the interpreter without passing a script file as a parameter brings up the following prompt: C:\>scala Welcome to Scala version 2.9.0.1 Type in expressions to have them evaluated. Type :help for more information. scala> Type the following text to the right of the Scala prompt and press the Enter key: scala> println("Hello, Scala!"); This will produce the following result: Hello, Scala! SCRIPT MODE PROGRAMMING: Let us look at a simple code that would print the words Hello, World! object HelloWorld { /* This is my first java program. TUTORIALS POINT Simply Easy Learning
} * This will print 'Hello World' as the output */ def main(args: Array[String]) { println("Hello, world!") // prints Hello World } Let's look at how to save the file, compile and run the program. Please follow the steps given below: 1. Open notepad and add the code as above. 2. Save the file as: HelloWorld.scala. 3. Open a command prompt window and go to the directory where you saved the program file. Assume it is C:\> 4. Type 'scalac HelloWorld.scala' and press enter to compile your code. If there are no errors in your code, the command prompt will take you to the next line. 5. Above command will generate a few class files in the current directory. One of them will be called HelloWorld.class. This is a bytecode, which will run on Java Virtual Machine (JVM). 6. Now, type 'scala HelloWorld' to run your program. 7. You will be able to see 'Hello, World!' printed on the window. C:\> scalac HelloWorld.scala C:\> scala HelloWorld Hello, World! Basic Syntax: About Scala programs, it is very important to keep in mind the following points. Case Sensitivity - Scala is case-sensitive, which means identifier Hello and hello would have different meaning in Scala. Class Names - For all class names, the first letter should be in Upper Case. If several words are used to form a name of the class, each inner word's first letter should be in Upper Case. Example class MyFirstScalaClass Method Names - All method names should start with a Lower Case letter. If several words are used to form the name of the method, then each inner word's first letter should be in Upper Case. Example def myMethodName() Program File Name - Name of the program file should exactly match the object name. When saving the file, you should save it using the object name (Remember scala is case-sensitive) and append '.scala' to the end of the name (if the file name and the object name do not match your program will not compile). Example: Assume 'HelloWorld' is the object name. Then, the file should be saved as 'HelloWorld.scala' def main(args: Array[String]) - Scala program processing starts from the main() method, which is a mandatory part of every Scala Program. TUTORIALS POINT Simply Easy Learning
Page 1 and 2: Scala Tutorial
Page 3 and 4: ABOUT THE TUTORIAL Scala Tutorial S
Page 5 and 6: FLOATING POINT LITERALS ...........
Page 7 and 8: Scala Strings .....................
Page 9 and 10: CHAPTER 1 Scala Overview Scala, sho
Page 11 and 12: CHAPTER 2 Scala Environment Setup T
Page 13: $scala -version Scala code runner v
Page 17 and 18: forSome If implicit import Lazy Mat
Page 19 and 20: CHAPTER 4 Scala Data Types Scala ha
Page 21 and 22: Characters must not necessarily be
Page 23 and 24: Variable Type Inference: When you a
Page 25 and 26: The access to f in class Sub is OK
Page 27 and 28: var a = 10; var b = 20; var c = 25;
Page 29 and 30: } } println("a && b = " + (a&&b) );
Page 31 and 32: a >>> 15 C:/> Assignment Operators:
Page 33 and 34: Here, operators with the highest pr
Page 35 and 36: } If the boolean expression evaluat
Page 37 and 38: Nested if...else Statement: It is a
Page 39 and 40: while loop do...while loop for loop
Page 41 and 42: Flow Diagram: Example: object Test
Page 43 and 44: When the above code is compiled and
Page 45 and 46: } } // for loop execution with mult
Page 47 and 48: Flow Diagram: Example: import scala
Page 49 and 50: Infinite Loop: A loop becomes infin
Page 51 and 52: } } return sum A function, which do
Page 53 and 54: When the above code is compiled and
Page 55 and 56: } When the above code is compiled a
Page 57 and 58: } logWithDateBound("message1" ) log
Page 59 and 60: CHAPTER 12 Scala Strings Consider t
Page 61 and 62: } } var str2 = "Tod"; println("Dot
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CHAPTER 13 Scala Arrays Scala provi
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C:/> Multi-Dimensional Arrays: Ther
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C:/> Scala Arrays Methods: Followin
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Scala Lists Scala Lists are quite s
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Creating Uniform Lists: You can use
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13 14 15 16 17 18 19 20 21 22 23 24
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var s = Set(1,3,5,7) While defining
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C:/> Scala Set Methods: Following a
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elements. 38 39 40 41 42 43 44 45 4
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use two maps with ++ as method colo
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11 12 13 14 15 16 17 18 19 20 21 22
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val t = new Tuple3(1, "hello", Cons
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The method will return Some[Person]
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6 7 8 9 10 11 12 13 14 def filter(p
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Scala Iterator Methods: Following a
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38 39 40 41 42 43 44 45 46 47 48 49
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CHAPTER 15 Scala Classes & Objects
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} } println ("Point y location : "
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CHAPTER 16 Scala Traits A trait enc
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CHAPTER 17 Scala Pattern Matching P
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} // case class, empty one. case cl
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} When the above code is compiled a
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[0-9] Match any digit; same as [012
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CHAPTER 19 Scala Exception Handling
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CHAPTER 20 Scala Extractors An extr
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CHAPTER 21 Scala Files I/O Scala is
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