What is the meaning of a=> in the below code? is it a pointer like this to the instantiated object?
class A {
  a=>
  def methodB()={
     .....
  }
}
It is called a self reference or self type. In your case it means "create a symbol of name 'a' and point it to the this reference".
See the SO Scala tutorial in section "Self references" (chapter 17) for more information: