Add feature to add items into ItemList

src/main/java/seedu/binbash/ItemList.java

@@ -17,8 +17,13 @@ public List<Item> getItemList() {
     /**
      * Test method
      */
-    public void addItem(Item item) {
+    public String addItem(String itemName, String itemDescription) {
+        Item item = new Item(itemName, itemDescription);
         itemList.add(item);
+
+        String output = "Noted! I have added the following item into your inventory:"
+                + String.format("\t%s", item);
+        return output;
     }
 
     public String deleteItem(int index) {

src/main/java/seedu/binbash/command/AddCommand.java

@@ -0,0 +1,23 @@
+package seedu.binbash.command;
+
+import java.util.regex.Pattern;
+import seedu.binbash.ItemList;
+
+public class AddCommand extends Command {
+    public static final String COMMAND_STRING = "add";
+    public static final Pattern COMMAND_FORMAT =
+            Pattern.compile("add\\s/n(?<itemName>\\s+)\\s/d(?<itemDescription>\\s+)");
+    private String itemName;
+    private String itemDescription;
+
+    public AddCommand(ItemList itemList, String itemName, String itemDescription) {
+        super(itemList);
+        this.itemName = itemName;
+        this.itemDescription = itemDescription;
+    }
+
+    @Override
+    public String execute() {
+        return itemList.addItem(itemName, itemDescription);
+    }
+}