Option (Some & None) Example

Option is the abstract class for which 2 concrete subclasses are Some & None

Some : Represents the presence of Data
None : Represents the absence of Data

scala> //#PS:58

scala> val marks = Map(    "english" -> 80,
     |                     "math" -> 75,
     |                     "history" -> 85)
marks: scala.collection.immutable.Map[String,Int] = Map(english -> 80, math -> 75, history -> 85)

scala>

scala> //Retrieving the Option(can be Some or None)

scala> marks.get("english")
res5: Option[Int] = Some(80)

scala> marks.get("science")
res6: Option[Int] = None

scala>

scala> //Retrieving the Values

scala> marks.get("english").get
res7: Int = 80

scala> marks.get("science").get
java.util.NoSuchElementException: None.get
        at scala.None$.get(Option.scala:313)
        at scala.None$.get(Option.scala:311)
        at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:22)
        at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:27)
        at $iwC$$iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:29)
        at $iwC$$iwC$$iwC$$iwC$$iwC.<init>(<console>:31)
        at $iwC$$iwC$$iwC$$iwC.<init>(<console>:33)
        at $iwC$$iwC$$iwC.<init>(<console>:35)
        at $iwC$$iwC.<init>(<console>:37)
        at $iwC.<init>(<console>:39)
        at <init>(<console>:41)
        at .<init>(<console>:45)
        at .<clinit>(<console>)
        at .<init>(<console>:7)
        at .<clinit>(<console>)
        at $print(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.spark.repl.SparkIMain$ReadEvalPrint.call(SparkIMain.scala:1065)
        at org.apache.spark.repl.SparkIMain$Request.loadAndRun(SparkIMain.scala:1340)
        at org.apache.spark.repl.SparkIMain.loadAndRunReq$1(SparkIMain.scala:840)
        at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:871)
        at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:819)
        at org.apache.spark.repl.SparkILoop.reallyInterpret$1(SparkILoop.scala:857)
        at org.apache.spark.repl.SparkILoop.interpretStartingWith(SparkILoop.scala:902)
        at org.apache.spark.repl.SparkILoop.command(SparkILoop.scala:814)
        at org.apache.spark.repl.SparkILoop.processLine$1(SparkILoop.scala:657)
        at org.apache.spark.repl.SparkILoop.innerLoop$1(SparkILoop.scala:665)
        at org.apache.spark.repl.SparkILoop.org$apache$spark$repl$SparkILoop$$loop(SparkILoop.scala:670)
        at org.apache.spark.repl.SparkILoop$$anonfun$org$apache$spark$repl$SparkILoop$$process$1.apply$mcZ$sp(SparkILoop.scala:997)
        at org.apache.spark.repl.SparkILoop$$anonfun$org$apache$spark$repl$SparkILoop$$process$1.apply(SparkILoop.scala:945)
        at org.apache.spark.repl.SparkILoop$$anonfun$org$apache$spark$repl$SparkILoop$$process$1.apply(SparkILoop.scala:945)
        at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
        at org.apache.spark.repl.SparkILoop.org$apache$spark$repl$SparkILoop$$process(SparkILoop.scala:945)
        at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:1059)
        at org.apache.spark.repl.Main$.main(Main.scala:31)
        at org.apache.spark.repl.Main.main(Main.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:672)
        at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:180)
        at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:205)
        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:120)
        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)


scala> marks.get("Science").getOrElse(50)
res9: Int = 50

Note : Sealed Hierarchy
#PS:60, 121
When a Class is Specified with the keyword sealed, the hierarchies for that class can only be created inside the same file. Option is a Sealed class, which has both Some & None defined in the same file
sealed abstract class Option[+A] extends Product with Serializable