MoreCollections

- Added comment

Collections/MoreCollections/MoreCollections/src/main/java/ocp/practice/collections/MoreCollections/App.java

@@ -1,5 +1,10 @@
 package ocp.practice.collections.MoreCollections;
 
+import java.util.ArrayList;
+import java.util.Collections;
+
+import com.sun.tools.javac.util.List;
+
 /**
  * More colelctions practicing
  *
@@ -8,6 +13,44 @@ public class App
 {
     public static void main(String[] args)
     {
+        ArrayList<Integer> numbers = new ArrayList<Integer>();
+        numbers.add(5);
+        numbers.add(4);
+        numbers.add(3);
+        numbers.add(2);
+        numbers.add(1);
         
+        /**
+         * Holds a bunch of sorting routines that
+         * can be applied on collections, such as
+         * a {@link List}
+         */
+        System.out.println("Before sort: "+numbers);
+        Collections.sort(numbers, (left, right) -> left-right);
+        System.out.println("After sort: "+numbers); // Sorts it IN-PLACE
+        Collections.reverse(numbers);
+        System.out.println("After reverse: "+numbers); // Revererses it IN-PLACE
+
+        
+        ArrayList<Integer> numbers2 = new ArrayList<Integer>();
+        numbers2.add(5);
+        numbers2.add(4);
+        numbers2.add(3);
+        numbers2.add(2);
+        numbers2.add(1);
+        
+        /**
+         * Worth noting that {@linkArrayList#sort}
+         * also exists
+         */
+        System.out.println("Before sort: "+numbers2);
+        numbers2.sort((left, right) -> left-right);
+        System.out.println("After sort: "+numbers2); // Sorts it IN-PLACE
+        
+        /**
+         * For reversal, the {@link Collections#reverse} class
+         * MUST be used as it does not exist in {@link List}
+         * NOR {@link ArrayList}
+         */
     }
 }