add defensive coding techniques

src/main/java/seedu/address/logic/commands/QueryDoctorAppointmentCommand.java

@@ -2,6 +2,7 @@
 
 import static java.util.Objects.requireNonNull;
 
+import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import seedu.address.commons.util.ToStringBuilder;
@@ -11,7 +12,7 @@
 
 /**
  * Represents a command for querying appointments for a specific doctor.
- * The command searches for appointments of doctors whose NRICs/names contain any of the specified keywords
+ * The command searches for appointments of doctors whose NRICs contain any of the specified keywords
  * (case-insensitive) and displays them as a list with index numbers.
  */
 public class QueryDoctorAppointmentCommand extends Command {
@@ -28,17 +29,27 @@ public class QueryDoctorAppointmentCommand extends Command {
 
     private final AppointmentContainsDoctorPredicate predicate;
 
+    /**
+     * Constructs a QueryDoctorAppointmentCommand with the given predicate.
+     *
+     * @param predicate The predicate to be used for querying doctor appointments.
+     * @throws NullPointerException if the predicate is null.
+     */
     public QueryDoctorAppointmentCommand(AppointmentContainsDoctorPredicate predicate) {
+        requireNonNull(predicate, "Predicate cannot be null in QueryDoctorAppointmentCommand constructor.");
         this.predicate = predicate;
     }
 
     @Override
     public CommandResult execute(Model model) {
-        requireNonNull(model);
-        logger.info("Executing QueryDoctorAppointmentCommand");
+        requireNonNull(model, "Model cannot be null in execute method of QueryDoctorAppointmentCommand.");
+
+        logger.log(Level.INFO, "Executing QueryDoctorAppointmentCommand");
+
         model.updateFilteredAppointmentList(predicate);
         int numberOfAppointments = model.getFilteredAppointmentList().size();
-        logger.info("Number of appointments found: " + numberOfAppointments);
+        logger.log(Level.INFO, "Number of appointments found: " + numberOfAppointments);
+
         return new CommandResult(
                 String.format(Messages.MESSAGE_APPOINTMENTS_LISTED_OVERVIEW, numberOfAppointments));
     }
@@ -49,7 +60,6 @@ public boolean equals(Object other) {
             return true;
         }
 
-        // instanceof handles nulls
         if (!(other instanceof QueryDoctorAppointmentCommand)) {
             return false;
         }

src/main/java/seedu/address/logic/commands/QueryPatientAppointmentCommand.java

@@ -12,7 +12,7 @@
 
 /**
  * Represents a command for querying appointments for a specific patient.
- * The command searches for appointments of patients whose NRICs/names contain any of the specified keywords
+ * The command searches for appointments of patients whose NRICs contain any of the specified keywords
  * (case-insensitive) and displays them as a list with index numbers.
  */
 public class QueryPatientAppointmentCommand extends Command {
@@ -28,17 +28,27 @@ public class QueryPatientAppointmentCommand extends Command {
 
     private final AppointmentContainsPatientPredicate predicate;
 
+    /**
+     * Constructs a QueryPatientAppointmentCommand with the given predicate.
+     *
+     * @param predicate The predicate to be used for querying patient appointments.
+     * @throws NullPointerException if the predicate is null.
+     */
     public QueryPatientAppointmentCommand(AppointmentContainsPatientPredicate predicate) {
+        requireNonNull(predicate, "Predicate cannot be null in QueryPatientAppointmentCommand constructor.");
         this.predicate = predicate;
     }
 
     @Override
     public CommandResult execute(Model model) {
-        requireNonNull(model);
+        requireNonNull(model, "Model cannot be null in execute method of QueryPatientAppointmentCommand.");
+
         logger.log(Level.INFO, "Executing QueryPatientAppointmentCommand");
+
         model.updateFilteredAppointmentList(predicate);
         int numberOfAppointments = model.getFilteredAppointmentList().size();
         logger.log(Level.INFO, "Number of appointments found: " + numberOfAppointments);
+
         return new CommandResult(
                 String.format(Messages.MESSAGE_APPOINTMENTS_LISTED_OVERVIEW, numberOfAppointments));
     }
@@ -49,7 +59,6 @@ public boolean equals(Object other) {
             return true;
         }
 
-        // instanceof handles nulls
         if (!(other instanceof QueryPatientAppointmentCommand)) {
             return false;
         }

src/main/java/seedu/address/logic/commands/QueryPatientCommand.java

@@ -11,9 +11,10 @@
 import seedu.address.model.person.PatientContainsKeywordsPredicate;
 
 /**
- * Queries and returns all patients whose name matches the input string.
- * Keyword matching is case insensitive.
- * Query more than one name at a time is supported
+ * Queries and returns all patients whose name, NRIC, DoB and phone number matches
+ * or substring matches the input string.
+ * Keyword matching is case-insensitive.
+ * Query more than one name, nric, date of birth and phone number at a time is supported
  */
 public class QueryPatientCommand extends Command {
 
@@ -28,17 +29,27 @@ public class QueryPatientCommand extends Command {
 
     private final PatientContainsKeywordsPredicate predicate;
 
+    /**
+     * Constructs a QueryPatientCommand with the given predicate.
+     *
+     * @param predicate The predicate to be used for querying patients.
+     * @throws NullPointerException if the predicate is null.
+     */
     public QueryPatientCommand(PatientContainsKeywordsPredicate predicate) {
+        requireNonNull(predicate, "Predicate cannot be null in QueryPatientCommand constructor.");
         this.predicate = predicate;
     }
 
     @Override
     public CommandResult execute(Model model) {
-        requireNonNull(model);
+        requireNonNull(model, "Model cannot be null in execute method of QueryPatientCommand.");
+
         logger.log(Level.INFO, "Executing QueryPatientCommand");
+
         model.updateFilteredPersonList(predicate);
         int numberOfPatients = model.getFilteredPersonList().size();
         logger.log(Level.INFO, "Number of patients found: " + numberOfPatients);
+
         return new CommandResult(
                 String.format(Messages.MESSAGE_PERSONS_LISTED_OVERVIEW, numberOfPatients));
     }
@@ -49,7 +60,6 @@ public boolean equals(Object other) {
             return true;
         }
 
-        // instanceof handles nulls
         if (!(other instanceof QueryPatientCommand)) {
             return false;
         }