Comment justifies instanceof in ConjureCollections#addAll (#24)

palantir · Jul 3, 2018 · 569b017 · 569b017
1 parent 5243f5e
commit 569b017
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/conjure-lib/src/main/java/com/palantir/conjure/java/lib/internal/ConjureCollections.java b/conjure-lib/src/main/java/com/palantir/conjure/java/lib/internal/ConjureCollections.java
@@ -31,6 +31,8 @@ private ConjureCollections() {
     @SuppressWarnings("unchecked")
     public static <T> void addAll(Collection<T> addTo, Iterable<? extends T> elementsToAdd) {
         if (elementsToAdd instanceof Collection) {
+            // This special-casing allows us to take advantage of the more performant
+            // ArrayList#addAll method which does a single System.arraycopy.
             addTo.addAll((Collection<T>) elementsToAdd);
         } else {
             for (T element : elementsToAdd) {