scala> val a = Array(1,2,3,4,5)
 a: Array[Int] = Array(1, 2, 3, 4, 5)
 for (i <- 0 until (a.length, 2)) {
     if (i + 1 < a.length) {
         var tmp = a(i)
         a(i) = a(i+1)
         a(i+1) = tmp
 scala> a
 res3: Array[Int] = Array(2, 1, 4, 3, 5)
    
用yield生成新数组
    
 scala> val a = Array(1,2,3,4,5)
 a: Array[Int] = Array(1, 2, 3, 4, 5)
 for (i <- 0 until a.length) yield {
     if (i % 2 == 0) {
         if (i + 1 < a.length) a(i+1) else a(i)
     } else {
         if (i - 1 >= 0) a(i-1) else a(i)
 res2: scala.collection.immutable.IndexedSeq[Int] = Vector(2, 1, 4, 3, 5)
    
给定一个数组，产出新的数组，正值在前;0和负数在后，两者都保持原顺序不变。
    
 scala> val a = Array(0,1,-2,-3,4,5,-6)
 a: Array[Int] = Array(0, 1, -2, -3, 4, 5, -6)
 scala> a.filter(_ > 0) ++ a.filter(_ <= 0)
 res5: Array[Int] = Array(1, 4, 5, 0, -2, -3, -6)
    
 scala> val b = Array(0,1.44,-2.0,-3.1,4,5.99,-6)
 b: Array[Double] = Array(0.0, 1.44, -2.0, -3.1, 4.0, 5.99, -6.0)
 scala> b.sum / b.length
 res7: Double = 0.04714285714285715
    
Array[Int]和ArrayBuffer[Int]都可以用reverse方法反序排列。此题的用意是神马？难道Scala 2.8版本有什么特别吗？
    
数组排重用ArrayOps.distinct
    
 scala> a
 res17: Array[Int] = Array(1, 2, 4, 3, 4, 5)
 scala> a.distinct
 res18: Array[Int] = Array(1, 2, 4, 3, 5)
    
收集负值下标，反序，去掉最后一个。
    
 val indexes = for (i <- 0 until a.length if a(i) < 0) yield i
 for (i <- indexes.reverse.init) a.remove(i) 
scala> val flavors =
SystemFlavorMap.getDefaultFlavorMap().asInstanceOf[SystemFlavorMap]
flavors: java.awt.datatransfer.SystemFlavorMap =
java.awt.datatransfer.SystemFlavorMap@1365301
scala> import scala.collection.mutable.Buffer
import scala.collection.mutable.Buffer
scala> import scala.collection.JavaConversions.asScalaBuffer
import scala.collection.JavaConversions.asScalaBuffer
scala> val b: Buffer[java.lang.String] = flavors.getNativesForFlavor(DataFlavor.imageFlavor)
b: scala.collection.mutable.Buffer[java.lang.String] = Buffer(image/jpeg,
image/png, image/x-png, image/gif, PNG, JFIF)