Question

I’m trying to do something like the following

  def defined(hash: HashMap[T, U], key: [T) {
    hash.contains(key)
  }

The above does not compile because my syntax is incorrect. Is it possible to check if a HashMap of unknown type contains a given key?

Answer 1

Other than the stray “[” I don’t think you have a syntax error. That and you need an “=” before your braces, or the function won’t be returning the bool. And since there is only one expression, no need for braces…

import scala.collection.mutable._

object Main extends App {

  def defined[T,U](hash: HashMap[T, U], key: T) = hash.contains(key)

  val m = new HashMap[String,Int]
  m.put("one", 1)
  m.put("two", 2)
  println(defined(m, "one"))
  println(m contains "two")
  println(defined(m, "three"))
}