How to convert java 8 map, filter and streams to scala?
<p>I am very new to scala trying to understand by changing the equivalent java to scala so that I get better understanding. </p>

<p>How to convert java 8 map, filter and streams to scala ? </p>

<p>I have the following java 8 code which I am trying to convert to Scala :</p>

<pre><code> public Set&lt;String&gt; getValidUsages(String itemId, long sNo, Date timeOfAccess) {                                                     
     Set&lt;String&gt; itemSet = Sets.newHashSet();                                                                                                   
     TestWindows testWindows = items.get(itemId).getTestWindows();                                                          

     final boolean isTV = existsEligibleTestWindow(testWindows.getTV(), timeOfAccess);                                       
     if (isTV) {                                                                                                                              
         itemSet.add(TV);                                                                                                              
     } else {                                                                                                                                    
         final boolean isCableUseable = existsEligibleTestWindow(testWindows.getCableUse(), timeOfAccess);                         
         final boolean isWifi = existsEligibleTestWindow(testWindows.getWifi(), timeOfAccess);                               
         if (isCableUseable || isWifi) {                                                                                                     
             itemSet.add(MOVIE);                                                                                                           
         }                                                                                                                                       
     }                                                                                                                                           

     if (testWindows.getUsageIds() != null) {                                                                                           
         itemSet.addAll(testWindows.getUsageIds()                                                                                      
                 .entrySet()                                                                                                                     
                 .stream()                                                                                                                       
                 .filter(entry -&gt; existsEligibleTestWindow(entry.getValue(), timeOfAccess))                                               
                 .map(Map.Entry::getKey)                                                                                                         
                 .collect(Collectors.toSet()));                                                                                                  
     }                                                                                                                                           

     return itemSet;                                                                                                                            
 }                                                                                                                                               

 private boolean existsEligibleTestWindow(List&lt;TestWindow&gt; windows, Date timeOfAccess) {                                           
     if (windows != null) {                                                                                                                      
         return windows.stream()                                                                                                                 
                 .filter(w -&gt; withinDateRange(timeOfAccess, w))                                                                                  
                 .findAny()                                                                                                                      
                 .isPresent();                                                                                                                   
     }                                                                                                                                           
     return false;                                                                                                                               
 }                                                                                                                                               

 private boolean withinDateRange(Date toCheck, TestWindow window) {                                                                       
     return toCheck.after(window.getStartTime()) &amp;&amp; toCheck.before(window.getEndTime());                                                         
 }  
</code></pre>

<p>I tried :</p>

<pre><code> def withinDateRange(toCheck: Date, window: TestWindow): Boolean = {
    toCheck.after( window.getStartTime ) &amp;&amp; toCheck.before( window.getEndTime )
  }


  def getValidUsages(itemId: String, sNo: Long, timeOfAccess: Date): Set[String] = {
    var itemSet = Sets.newHashSet()
    val testWindows = items.value(itemId).getTestWindows
    val isTV = existsEligibleTestWindow(testWindows.get(0).getTV, timeOfAccess)
    if (isTV) {
      itemSet += TV
    } else {
      val isCableUseable = existsEligibleTestWindow(testWindows.get(0).getCableUse, timeOfAccess)
      val isWifi = existsEligibleTestWindow(testWindows.get(0).getWifi, timeOfAccess)
      if (isCableUseable || isWifi) {
        itemSet += MOVIE
      }
    }
    if (testWindows.get(0).getUsageIds != null) {
      itemSet.addAll(testWindows.get(0).getUsageIds.entrySet().stream()
        .filter((x) =&gt; existsEligibleTestWindow(x._2, timeOfAccess)).map(x =&gt; Map.Entry._1 )
        .collect(Collectors.toSet()))
    }
    itemSet
  }


   def existsEligibleConsumptionWindow(windows: List[ConsumptionWindow], timeOfAccess: Date): Boolean = {
if (windows != null) {
  return windows.exists((x) =&gt; withinDateRange(timeOfAccess, x))
}
false
}
</code></pre>

<p>But getting error while doing filter and stream. Can some one point to direct direction ? Any references ?  I am getting error on getValidUsages : </p>

<pre><code> compile error “cannot resolve reference project with such signature
</code></pre>