home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Scala example source code file (t2526.scala)

This example Scala source code file (t2526.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Scala tags/keywords

array, array, iterator, list, string, test, test, traversable, traversable, unit, unit

The Scala t2526.scala source code

/**
 * Checks that various foreach methods overridden in mutable.HashMap as part of ticket #2526
 * still work correctly.
 */
object Test {
  import collection._
  
  def main(args: Array[String]) {
    val m = new mutable.HashMap[String, String]
    
    /* Use non hash-based structure for verification */
    val keys = List("a", "b", "c", "d", "e")
    val valueSuffix = "value"
    val values = keys.map(_ + valueSuffix)
    val entries = keys.zip(values)
    
    for (k <- keys) m(k) = k + valueSuffix
    
    assertForeach(keys, m.keySet.iterator)
    assertForeach(keys, m.keysIterator)
    assertForeach(keys, m.keySet)

    assertForeach(values, m.values.iterator)
    assertForeach(values, m.valuesIterator)

    assertForeach(entries, m)
  }
  
  /* Checks foreach of `actual` goes over all the elements in `expected` */
  private def assertForeach[E](expected: Traversable[E], actual: Iterator[E]): Unit = {
    val notYetFound = new mutable.ArrayBuffer[E]() ++= expected
    actual.foreach { e =>
      assert(notYetFound.contains(e))
      notYetFound -= e
    }
    assert(notYetFound.size == 0, "mutable.HashMap.foreach should have iterated over: " + notYetFound)
  }
  
  /* 
   * Checks foreach of `actual` goes over all the elements in `expected`
   * We duplicate the method above because there is no common inteface between Traversable and
   * Iterator and we want to avoid converting between collections to ensure that we test what
   * we mean to test. 
   */
  private def assertForeach[E](expected: Traversable[E], actual: Traversable[E]): Unit = {
    val notYetFound = new mutable.ArrayBuffer[E]() ++= expected
    actual.foreach { e =>
      assert(notYetFound.contains(e))
      notYetFound -= e
    }
    assert(notYetFound.size == 0, "mutable.HashMap.foreach should have iterated over: " + notYetFound)
  }
}

Other Scala examples (source code examples)

Here is a short list of links related to this Scala t2526.scala source code file:



my book on functional programming

 

new blog posts

 

Copyright 1998-2019 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.