[Sync Iteration] java/gotta-snatch-em-all/1

solutions/java/gotta-snatch-em-all/1/src/main/java/GottaSnatchEmAll.java

@@ -0,0 +1,43 @@
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+class GottaSnatchEmAll {
+
+    static Set<String> newCollection(List<String> cards) {
+    return new HashSet<> (cards);
+    }
+
+    static boolean addCard(String card, Set<String> collection) {       
+        return collection.add(card);
+    }
+
+    static boolean canTrade(Set<String> myCollection, Set<String> theirCollection) {
+        Set<String> myExtras = new HashSet<>(myCollection);
+        Set<String> theirExtras = new HashSet<>(theirCollection);
+
+        // Remove common cards
+        myExtras.removeAll(theirCollection);
+        theirExtras.removeAll(myCollection);
+
+        return (myExtras.size() > 0) && (theirExtras.size() > 0);
+
+    }
+
+    static Set<String> commonCards(List<Set<String>> collections) {
+        Set<String> common = new HashSet<> (collections.get(0));
+
+        for(Set<String> c : collections){
+            common.retainAll(c);
+        }
+        return common;
+    }
+
+    static Set<String> allCards(List<Set<String>> collections) {
+        Set<String> all = new HashSet<>();
+        for(Set<String> c : collections){
+            all.addAll(c);
+        }
+        return all;
+    }
+}