optimization as respond to comments

Author: hhbyyh

mllib/src/main/scala/org/apache/spark/mllib/util/MLUtils.scala

@@ -86,10 +86,11 @@ object MLUtils {
         // check if indices are one-based and in ascending order
         var previous = -1
         var i = 0
-        val indicesLength = indices.size
+        val indicesLength = indices.length
         while (i < indicesLength) {
-          require(indices(i) > previous, "indices should be one-based and in ascending order" )
-          previous = indices(i)
+          val current = indices(i)
+          require(current > previous, "indices should be one-based and in ascending order" )
+          previous = current
           i += 1
         }