MINOR: Optimize KTable-KTable join value getter supplier (#4458)

kamilszymanski · guozhangwang · commit b5da5f8bec2b · 2018-01-28T20:17:48.000-08:00
Reviewers: Guozhang Wang &lt;wangguoz@gmail.com&gt;, Damian Guy &lt;damian.guy@gmail.com&gt;, Matthias J. Sax &lt;mjsax@apache.org&gt;
diff --git a/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KTableKTableAbstractJoinValueGetterSupplier.java b/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KTableKTableAbstractJoinValueGetterSupplier.java
@@ -17,6 +17,7 @@
 package org.apache.kafka.streams.kstream.internals;
 
 import java.util.ArrayList;
+import java.util.Collections;
 
 public abstract class KTableKTableAbstractJoinValueGetterSupplier<K, R, V1, V2> implements KTableValueGetterSupplier<K, R> {
     final KTableValueGetterSupplier<K, V1> valueGetterSupplier1;
@@ -33,12 +34,8 @@ public String[] storeNames() {
         final String[] storeNames1 = valueGetterSupplier1.storeNames();
         final String[] storeNames2 = valueGetterSupplier2.storeNames();
         final ArrayList<String> stores = new ArrayList<>(storeNames1.length + storeNames2.length);
-        for (final String storeName : storeNames1) {
-            stores.add(storeName);
-        }
-        for (final String storeName : storeNames2) {
-            stores.add(storeName);
-        }
+        Collections.addAll(stores, storeNames1);
+        Collections.addAll(stores, storeNames2);
         return stores.toArray(new String[stores.size()]);
     }
 
