Minor changes: coding style and thread safety

src/main/scala/BlurCaptcha.scala

@@ -19,13 +19,6 @@ class BlurCaptcha extends CaptchaProvider {
     challenge
   }
   def checkAnswer(token: String, input: String): Boolean = {
-    if(tokenAnswer(token)==input)
-    {
-      true
-    }
-    else
-    {
-      false
-    }
+    tokenAnswer(token) == input
   }
 }

src/main/scala/FilterCaptcha.scala

@@ -12,7 +12,9 @@ class FilterCaptcha extends CaptchaProvider {
     val n = 8
     val answer = Stream.continually(r.nextInt(alphabet.size)).map(alphabet).take(n).mkString
     val token = scala.util.Random.nextInt(10000).toString
-    tokenAnswer += token -> answer
+    tokenAnswer += synchronized {
+      token -> answer
+    }
     val canvas = new BufferedImage(225, 50, BufferedImage.TYPE_INT_RGB)
     val g = canvas.createGraphics()
     g.setColor(Color.WHITE)
@@ -28,14 +30,7 @@ class FilterCaptcha extends CaptchaProvider {
     challenge
   }
   def checkAnswer(token: String, input: String): Boolean = {
-    if(tokenAnswer(token)==input)
-    {
-      true
-    }
-    else
-    {
-      false
-    }
+    tokenAnswer(token) == input
   }
 }
 

src/main/scala/LabelCaptcha.scala

@@ -43,19 +43,16 @@ class LabelCaptcha extends CaptchaProvider {
     val userAnswer = input.split(' ')
     if(userAnswer(0)==expectedAnswer) {
       val unknownFile = tokenImagePair(token).unknown
-      if((unknownAnswers(unknownFile)).contains(userAnswer(1)))
-      {
+      if((unknownAnswers(unknownFile)).contains(userAnswer(1))) {
         unknownAnswers(unknownFile)(userAnswer(1)) += 1
         total(unknownFile) += 1
       }
-      else
-      {
+      else {
         unknownAnswers(unknownFile)+=(userAnswer(1)) -> 1
         total(unknownFile) += 1
       }
       if(total(unknownFile)>=3) {
-        if((unknownAnswers(unknownFile)(userAnswer(1))/total(unknownFile))>=0.9)
-        {
+        if((unknownAnswers(unknownFile)(userAnswer(1))/total(unknownFile))>=0.9) {
           unknownAnswers -= unknownFile
           Files.move(new File("unknown/"+unknownFile).toPath, new File("known/"+userAnswer(1)+".png").toPath, StandardCopyOption.REPLACE_EXISTING)
           knownFiles = new File("known").list.toList