Added sort and compare collection methods

Author: Diego Domínguez

src/main/java/com/seniorglez/functionalJava/collections/CollectionsUtils.java

@@ -25,6 +25,8 @@
 
 import java.lang.reflect.Constructor;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
@@ -176,7 +178,7 @@ public static <T> Collection<T> concat(Collection<T> a, Collection<T> b) {
     }
 
     /**
-     * Return a new List which the elements of the given collections.
+     * Return a new List which the elements of the given Lists.
      *
      * @param a First List given.
      * @param b Second List given.
@@ -204,6 +206,32 @@ public static <T> T last(Collection<T> collection) {
         return toList(collection).get(collection.size() - 1);
     }
 
+
+    /**
+     * Return true if the collections have the same elements.
+     *
+     * @param a First Collection given.
+     * @param b Second Collection given.
+     * @param comparator The comparator needed to sort the elements.
+     */
+    public static <T> boolean compareCollections(Collection<T> a, Collection<T> b, Comparator<T> comparator) {
+        Collection <T> sortedA = sort(a,  comparator);
+        Collection <T> sortedB = sort(a,  comparator);
+        return sortedA.equals(sortedB);
+    }
+
+    /**
+     * Return a new sorted List from the given collection.
+     *
+     * @param collection The Collection given.
+     * @param comparator The comparator needed to sort the elements.
+     */
+    public static <T> List<T> sort(Collection<T> collection, Comparator<T> comparator) {
+        List<T> list = toList(collection);
+        Collections.sort(list,comparator);
+        return list;
+    }
+
     //private methods
 
     private static Collection instanceCollectionOf(Class<? extends Collection> tClass) {

src/test/java/com/seniorglez/functionalJava/collections/TestCollectionsUtils.java

@@ -4,15 +4,18 @@
 import org.junit.Test;
 
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.LinkedList;
 import java.util.List;
 
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.anyMatch;
+import static com.seniorglez.functionalJava.collections.CollectionsUtils.compareCollections;
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.concat;
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.findIndex;
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.first;
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.isEmpty;
 import static com.seniorglez.functionalJava.collections.CollectionsUtils.last;
+import static com.seniorglez.functionalJava.collections.CollectionsUtils.sort;
 import static org.junit.Assert.assertTrue;
 
 public class TestCollectionsUtils {
@@ -282,4 +285,29 @@ public void testLast() {
         assertTrue(last(a) == "Urdin");
     }
 
+    @Test
+    public void testCompareCollectionsShouldReturnTrue() {
+        Collection<String> a = new LinkedList<>();
+        a.add("Gorri");
+        a.add("Beltz");
+        a.add("Hori");
+        a.add("Urdin");
+        Collection<String> b = new LinkedList<>();
+        b.add("Beltz");
+        b.add("Gorri");
+        b.add("Hori");
+        b.add("Urdin");
+        assertTrue(compareCollections(a,b, Comparator.naturalOrder()));
+    }
+
+    @Test
+    public void  testNaturalOrderSort() {
+        Collection<String> a = new LinkedList<>();
+        a.add("Gorri");
+        a.add("Beltz");
+        a.add("Hori");
+        a.add("Urdin");
+        assertTrue(sort(a, Comparator.naturalOrder()).get(0).equals("Beltz"));
+    }
+
 }