This document introduces using VI Java, a Java performance analysis tool, from Scala. It provides a quick overview of Scala concepts like val and var for variables, Lists, Arrays, mapping functions, singleton objects, and pattern matching using match. These concepts are demonstrated in code examples to visualize VI Java metrics from Scala and show how Scala interoperates well with Java libraries.

1. Using VI Java from Scala
Dave “Bric” Briccetti, Contractor at VMware
Dave Briccetti Software LLC
davebsoft.com
@dcbriccetti

2. VI Java for Performance Graphs

3. HelloVM.scala

4. Quick Intro to Scala
(Enough to read the code)
● val and var
● List
● Array
● map
● Singleton object
● match

5. val and var
● val creates a final variable
val x = 1
x=2
error: reassignment to val
var x = 1
x=2

6. List
● val nums = List(2,5,8)
nums: List[Int] = List(2, 5, 8)
nums.size
res9: Int = 3

7. Array
● val nums = Array(1,5,7)
nums: Array[Int] = Array(1, 5, 7)
nums.toList
res8: List[Int] = List(1, 5, 7)

8. map
● val nums = List(2,5,8)
nums: List[Int] = List(2, 5, 8)
nums.map(_ + 1)
res10: List[Int] = List(3, 6, 9)

9. Singleton Object
● Java types:
● class
● interface
● Scala types:
● class
● trait
● object
● object is like a preinstantiated object of a class,
with all members static

10. match
● List(2) match {
case first :: rest => "First: " + first + ", rest: " + rest
case _ => "no match"
}
res17: java.lang.String = First: 2, rest: List()
● List(2,3) match {
case first :: rest => "First: " + first + ", rest: " + rest
case _ => "no match"
}
res18: java.lang.String = First: 2, rest: List(3)

11. Unit Test

12. HelloVM Part 1

13. HelloVM Part 2

14. HelloVM Part 3

15. Summary
● The Java Virtual Machine runs many
languages, including Scala
● VI Java can be used by any of these languages
● Scala is a powerful language, which
interoperates very well with Java libraries like VI
Java
Dave Briccetti Software LLC
davebsoft.com
@dcbriccetti