Rename at/by to atDateTime/byDateTime to avoid ambiguity

src/main/java/duke/Parser.java

@@ -80,9 +80,8 @@ public Command parse(String fullCommand) throws InvalidInputException {
         }
 
         // Store the last k-v pair
-        if (!values.isEmpty()) {
-            arguments.put(key, String.join(DELIMITER, values));
-        }
+        // Store even when `values` is empty, as that indicates an empty string
+        arguments.put(key, String.join(DELIMITER, values));
 
         // Initialize a respective class from the command (by capitalize first character)
         String className = tokens[0] + "Command";

src/main/java/duke/task/Deadline.java

@@ -10,17 +10,17 @@ public class Deadline extends Task {
     // This value indicates the version of this class when doing serialization
     public static final long serialVersionUID = 2L;
 
-    protected DateTime by;
+    protected DateTime byDateTime;
 
     /**
      * Initialize the deadline task and set the typeIcon to 'D'
      * @param description Description of the task, cannot be empty
-     * @param by The date and time this task has to be done before
+     * @param byDateTime The date and time this task has to be done before
      * @throws InvalidInputException This is thrown if the task description is null or an empty string
      */
-    public Deadline(String description, DateTime by) throws InvalidInputException {
+    public Deadline(String description, DateTime byDateTime) throws InvalidInputException {
         super(description);
-        this.by = by;
+        this.byDateTime = byDateTime;
         typeIcon = "D";
     }
 
@@ -31,14 +31,14 @@ public Deadline(String description, DateTime by) throws InvalidInputException {
      */
     @Override
     public Boolean isSameDate(DateTime dateTime) {
-        return by.isSameDate(dateTime);
+        return byDateTime.isSameDate(dateTime);
     };
 
     /**
      * Converts this task to a descriptive string
      */
     @Override
     public String toString() {
-        return super.toString() + String.format(" (by: %s)", by);
+        return super.toString() + String.format(" (by: %s)", byDateTime);
     }
 }

src/main/java/duke/task/Event.java

@@ -10,17 +10,17 @@ public class Event extends Task {
     // This value indicates the version of this class when doing serialization
     public static final long serialVersionUID = 2L;
 
-    protected DateTime at;
+    protected DateTime atDateTime;
 
     /**
      * Initialize the event task and set the typeIcon to 'E'
      * @param description Description of the task, cannot be empty
-     * @param at The date and time this event falls at
+     * @param atDateTime The date and time this event falls at
      * @throws InvalidInputException This is thrown if the task description is null or an empty string
      */
-    public Event(String description, DateTime at) throws InvalidInputException {
+    public Event(String description, DateTime atDateTime) throws InvalidInputException {
         super(description);
-        this.at = at;
+        this.atDateTime = atDateTime;
         typeIcon = "E";
     }
 
@@ -31,14 +31,14 @@ public Event(String description, DateTime at) throws InvalidInputException {
      */
     @Override
     public Boolean isSameDate(DateTime dateTime) {
-        return at.isSameDate(dateTime);
+        return atDateTime.isSameDate(dateTime);
     };
 
     /**
      * Converts this task to a descriptive string
      */
     @Override
     public String toString() {
-        return super.toString() + String.format(" (at: %s)", at);
+        return super.toString() + String.format(" (at: %s)", atDateTime);
     }
 }