Scala

LEARN SCALA IN ONE DAY

In this post we’ll teach the Scala programming language on below topics and you will get good amount of knowledge of Scala Programming in a day which  you can use in Spark with Scala context.

We will cover installation Scala on Windows.We’ll also look at using the REPL versus compiling code. We’ll also cover Data Types, Math Functions, If, Main, While, Do While, For, receiving user input, Output Styling, Strings, Functions, Recursion, Arrays, Array Buffers, Yield, For Each, Maps, Tuples, Classes, Companion Objects, Inheritance, Abstract Classes, Traits, Higher Order Functions, Map, Filter, File I/O, Exception Handling and much more.

Scala Overview.

Scala, short for Scalable Language, is a hybrid functional programming language. It was created by Martin Odersky. Scala smoothly integrates the features of object-oriented and functional languages. Scala is compiled to run on the Java Virtual Machine. Many existing companies, who depend on Java for business critical applications, are turning to Scala to boost their development productivity, applications scalability and overall reliability.

Here we have presented a few points that makes Scala the first choice of application developers.

1. Scala is Object-Oriented

    Scala is a pure Object-Oriented Language which means that every value is an object.

2. Scala is functional

Scala is also a functional language in the sense that every function is a value and every value is an object so ultimately every function is an object.

3. Scala runs on the JVM

Scala is compiled into Java Byte Code which is executed by the Java Virtual Machine (JVM). This means that Scala and Java have a common runtime platform. You can easily move from Java to Scala.

4. Scala can Execute Java Code

Scala enables you to use all the classes of the Java SDK and also your own custom Java classes, or your favorite Java open source projects.

5. Scala can do Concurrent & Synchronize processing

Scala allows you to express general programming patterns in an effective way. It reduces the number of lines and helps the programmer to code in a type-safe way. It allows you to write codes in an immutable manner, which makes it easy to apply concurrency and parallelism (Synchronize).

6. Scala vs Java

Scala has a set of features that completely differ from Java. Some of these are

• All types are objects
• Type inference
• Nested Functions
• Functions are objects
• Domain specific language (DSL) support
• Traits
• Closures
• Concurrency support inspired by Erlang

Scala Installation

      The most useful command in Scala

Description	Command / Script	Comments
To open Scala in command prompt	scala	Type scala from comand prompt and hit Enter
To print the text	println	Example: println("Hello, Scala!");
Comments in Scala	// (For Single Line)  /* */ (For Multiline)	Example: // This is my First Scala Program Example: /* This is my first java program. This will print 'Hello World' as the output */
Compile the scala program	scalac	‘scalac’ command is used to compile the Scala program and it will generate a few class files in the current directory.Example: scalac Helloworld.scala
Execute the scala program.	scala	Example: scala Helloworld
Quit from Scala	:q	Example: Scala > q: <Enter>
To Clear the screen in Scala	cls	Type cls and press enter

      Basic Syntax  and coding conventions in Scala programming

Sr No	Basic Syntax	Syntax Descriptions
1	Case Sensitivity	Scala is case-sensitive, which means identifier Hello and hello would have different meaning in Scala.
2	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.
3	Method Names	All method names should start with a Lower Case letter. If multiple 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()
4	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'.
5	def main(args: Array[String])	Scala program processing starts from the main() method which is a mandatory part of every Scala Program.
6	To be added ...
7	To be added ...
8	To be added ...
9	To be added ...
10	To be added ...

  
      Data Types in Scala

Sr No	Data Type	Descriptions
1	Byte	8 bit signed value. Range from -128 to 127
2	Short	16 bit signed value. Range -32768 to 32767
3	Int	32 bit signed value. Range -2147483648 to 2147483647
4	Long	64 bit signed value. -9223372036854775808 to 9223372036854775807
5	Float	32 bit IEEE 754 single-precision float
6	Double	64 bit IEEE 754 double-precision float
7	Char	16 bit unsigned Unicode character. Range from U+0000 to U+FFFF
8	String	A sequence of Chars
9	Boolean	Either the literal true or the literal false
10	Unit	Corresponds to no value
11	Null	null or empty reference
12	Any	The supertype of any type; any object is of type Any
13	AnyRef	The supertype of any reference type
14
15

    Operators in Scala.

Operator	Description	Example
1. Arithmetic Operators in Scala: For example, let us assume variable A holds 10 and variable B holds 20, then
+	Adds two operands	A + B will give 30
-	Subtracts second operand from the first	A - B will give -10
*	Multiplies both operands	A * B will give 200
/	Divides numerator by de-numerator	B / A will give 2
%	Modulus operator finds the remainder after division of one number by another	B %
2. Relational Operators in Scala : For example let us assume variable A holds 10 and variable B holds 20, then
==	Checks if the values of two operands are equal or not, if yes then condition becomes true.	(A == B) is not true.
!=	Checks if the values of two operands are equal or not, if values are not equal then condition becomes true.	(A != B) is true.
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(A > B) is not true.
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(A < B) is true.
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(A >= B) is not true.
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(A <= B) is true.
3. Logical Operators in Scala : For example, assume variable A holds 1 and variable B holds 0, then
&&	It is called Logical AND operator. If both the operands are non zero then condition becomes true.	(A && B) is false.
||	It is called Logical OR Operator. If any of the two operands is non zero then condition becomes true.	(A || B) is true.
!	It is called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is true.
4. Assignment Operators in Scala
=	Simple assignment operator, Assigns values from right side operands to left side operand	C = A + B will assign value of A + B into C
+=	Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand	C += A is equivalent to C = C + A
-=	Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand	C -= A is equivalent to C = C - A
*=	Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand	C *= A is equivalent to C = C * A
/=	Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand	C /= A is equivalent to C = C / A
%=	Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand	C %= A is equivalent to C = C % A
<<=	Left shift AND assignment operator	C <<= 2 is same as C = C << 2
>>=	Right shift AND assignment operator	C >>= 2 is same as C = C >> 2
&=	Bitwise AND assignment operator	C &= 2 is same as C = C & 2
^=	bitwise exclusive OR and assignment operator	C ^= 2 is same as C = C ^ 2
|=	bitwise inclusive OR and assignment operator	C |= 2 is same as C = C | 2

Mathematical Functions in Scala

IF-ELSE conditions in Scala

WHILE and Do While in Scala

FOR LOOP in Scala

Receiving User Input in Scala

Functions in Scala