#1549: Add ctor to map.Merged

src/main/java/org/cactoos/map/Merged.java

@@ -24,8 +24,9 @@
 package org.cactoos.map;
 
 import java.util.Map;
-import java.util.stream.Collectors;
-import org.cactoos.list.ListOf;
+import org.cactoos.iterable.IterableOf;
+import org.cactoos.iterable.Joined;
+import org.cactoos.iterable.Mapped;
 
 /**
  * This class can be used to merge a few {@link Map}.
@@ -42,12 +43,22 @@ public final class Merged<K, V> extends MapEnvelope<K, V> {
      */
     @SafeVarargs
     public Merged(final Map<? extends K, ? extends V>... maps) {
+        this(new IterableOf<>(maps));
+    }
+
+    /**
+     * Ctor.
+     * @param maps Iterable of {@link Map}s to merge.
+     */
+    public Merged(final Iterable<? extends Map<? extends K, ? extends V>> maps) {
         super(
             new MapOf<>(
-                new ListOf<>(maps)
-                    .stream()
-                    .flatMap(map -> map.entrySet().stream())
-                    .collect(Collectors.toList())
+                new Joined<>(
+                    new Mapped<>(
+                        Map::entrySet,
+                        maps
+                    )
+                )
             )
         );
     }

src/test/java/org/cactoos/map/MergedTest.java

@@ -23,6 +23,8 @@
  */
 package org.cactoos.map;
 
+import org.cactoos.iterable.IterableOf;
+import org.hamcrest.core.AllOf;
 import org.hamcrest.core.IsEqual;
 import org.junit.Test;
 import org.llorllale.cactoos.matchers.Assertion;
@@ -31,21 +33,30 @@
  * Test case for {@link Merged}.
  *
  * @since 1.0
+ * @checkstyle ClassDataAbstractionCouplingCheck (500 lines)
  * @checkstyle JavadocMethodCheck (500 lines)
  */
 public final class MergedTest {
 
     @Test
+    @SuppressWarnings("unchecked")
     public void behavesAsMap() {
         new Assertion<>(
             "Must behave as a map",
-            new Merged<Integer, Integer>(
-                new MapOf<Integer, Integer>(
-                    new MapEntry<>(0, -1),
-                    new MapEntry<>(1, 1)
+            new Merged<>(
+                new MapOf<>(
+                    new MapEntry<>("a", 1)
+                ),
+                new MapOf<>(
+                    new MapEntry<>("b", 2)
                 )
             ),
-            new BehavesAsMap<>(1, 1)
+            new AllOf<>(
+                new IterableOf<>(
+                    new BehavesAsMap<>("a", 1),
+                    new BehavesAsMap<>("b", 2)
+                )
+            )
         ).affirm();
     }