Improve U.concat(iterables) method.

Author: terhesb

src/main/java/com/github/underscore/U.java

@@ -3169,17 +3169,11 @@ public static <T> T[] concat(final T[] first, final T[] ... other) {
      */
     @SuppressWarnings("unchecked")
     public static <T> List<T> concat(final Iterable<T> first, final Iterable<T> ... other) {
-        int length = 0;
-        for (Iterable<T> otherItem : other) {
-            length += size(otherItem);
-        }
-        final T[] result = Arrays.copyOf(toArray(first), size(first) + length);
-        int index = 0;
-        for (Iterable<T> otherItem : other) {
-            System.arraycopy(toArray(otherItem), 0, result, size(first) + index, size(otherItem));
-            index += size(otherItem);
+        List<T> list = newArrayList(first);
+        for (Iterable<T> iter : other) {
+            list.addAll(newArrayList(iter));
         }
-        return Arrays.asList(result);
+        return list;
     }
 
 

src/test/java/com/github/underscore/UnderscoreTest.java

@@ -147,13 +147,15 @@ public void compareStrings() {
     @SuppressWarnings("unchecked")
     public void concat() {
         assertEquals(asList(1, 2, 3, 4), asList(U.concat(new Integer[] {1, 2}, new Integer[] {3, 4})));
+        assertEquals(asList(1.0, 2.0), asList(U.concat(new Double[] {1.0, 2.0})));
         assertEquals(asList(1, 2, 3, 4), U.concat(asList(1, 2), asList(3, 4)));
-        assertEquals(asList(1, 2, 3, 4), new U(asList(1, 2)).concatWith(asList(3, 4)));
+        assertEquals(asList("a", "b"), U.concat(asList("a", "b")));
+        assertEquals(asList(1, 2, 3, 4), new U<Integer>(asList(1, 2)).concatWith(asList(3, 4)));
         assertEquals("[1, 2, 3, 4]", U.chain(asList(1, 2)).concat(asList(3, 4)).value().toString());
         assertEquals("[1, 2, 3, 4, 5, 6]", U.chain(asList(1, 2)).concat(asList(3, 4), asList(5, 6)).value().toString());
         assertEquals(asList(1, 2, 3, 4), asList(U.concat(new Integer[] {1, 2}, new Integer[] {3}, new Integer[] {4})));
         assertEquals(asList(1, 2, 3, 4), U.concat(asList(1, 2), asList(3), asList(4)));
-        assertEquals(asList(1, 2, 3, 4), new U(asList(1, 2)).concatWith(asList(3), asList(4)));
+        assertEquals(asList(1, 2, 3, 4), new U<Integer>(asList(1, 2)).concatWith(asList(3), asList(4)));
     }
 
 /*