Refactor command

src/main/java/seedu/binbash/BinBash.java

@@ -32,8 +32,8 @@ private void run() {
                     continue;
                 }
 
-                String executionResult = userCommand.execute();
-                userInterface.talk(executionResult);
+                userCommand.execute();
+                userInterface.talk(userCommand.getExecutionUiOutput());
                 storage.saveToStorage(itemList.getItemList());
 
             } catch (BinBashException e) {

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

@@ -42,8 +42,9 @@ public AddCommand(ItemList itemList, String itemName, String itemDescription, in
     }
 
     @Override
-    public String execute() {
-        return itemList.addItem(itemName, itemDescription, itemQuantity, itemExpirationDate,
+    public boolean execute() {
+        executionUiOutput = itemList.addItem(itemName, itemDescription, itemQuantity, itemExpirationDate,
                 itemSalePrice, itemCostPrice);
+        return true;
     }
 }

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

@@ -9,7 +9,8 @@ public ByeCommand(ItemList itemList) {
     }
 
     @Override
-    public String execute() {
-        return "";
+    public boolean execute() {
+        executionUiOutput = "";
+        return true;
     }
 }

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

@@ -6,11 +6,16 @@
 public abstract class Command {
     protected ItemList itemList;
     protected Logger commandLogger;
+    protected String executionUiOutput;
 
     protected Command(ItemList itemList) {
         this.itemList = itemList;
         commandLogger = Logger.getLogger("CommandLogger");
     }
 
-    public abstract String execute();
+    public String getExecutionUiOutput() {
+        return executionUiOutput;
+    }
+
+    public abstract boolean execute();
 }

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

@@ -30,15 +30,16 @@ public DeleteCommand(ItemList itemList, String keyword) {
         ));
     }
 
-    public String execute() {
+    public boolean execute() {
         if (isIndex) {
             // Ensure index out of bounds error is caught by Parser.
             assert index > 0 && index <= itemList.getItemCount();
             commandLogger.log(Level.INFO, "Delete identifier is detected as an index");
-            return itemList.deleteItem(index);
+            executionUiOutput = itemList.deleteItem(index);
+        } else {
+            commandLogger.log(Level.INFO, "Delete identifier is detected as an item name");
+            executionUiOutput = itemList.deleteItem(keyword);
         }
-
-        commandLogger.log(Level.INFO, "Delete identifier is detected as an item name");
-        return itemList.deleteItem(keyword);
+        return true;
     }
 }

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

@@ -9,7 +9,8 @@ public ListCommand(ItemList itemList) {
         commandLogger.fine("Creating List Command...");
     }
 
-    public String execute() {
-        return itemList.printList(itemList.getItemList());
+    public boolean execute() {
+        executionUiOutput = itemList.printList(itemList.getItemList());
+        return true;
     }
 }

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

@@ -18,7 +18,8 @@ public SearchCommand(ItemList itemList, String keyword) {
         ));
     }
 
-    public String execute() {
-        return itemList.searchItem(keyword);
+    public boolean execute() {
+        executionUiOutput = itemList.searchItem(keyword);
+        return true;
     }
 }

src/test/java/seedu/binbash/command/ListCommandTest.java

@@ -21,7 +21,8 @@ void execute_listCommandWithTwoItemsInItemList_correctPrintFormatForBothItems()
 
         ListCommand listCommand = new ListCommand(itemList);
 
-        String actualOutput = listCommand.execute();
+        listCommand.execute();
+        String actualOutput = listCommand.getExecutionUiOutput();
 
         String expectedOutput = "1. testItem1" + System.lineSeparator() +
                 "\tdescription: Test item 1" + System.lineSeparator() +