diff --git a/src/seedu/addressbook/AddressBook.java b/src/seedu/addressbook/AddressBook.java
index 5a158b67..50b0957f 100644
--- a/src/seedu/addressbook/AddressBook.java
+++ b/src/seedu/addressbook/AddressBook.java
@@ -141,9 +141,7 @@ public class AddressBook {
      * used by the internal String[] storage format.
      * For example, a person's name is stored as the 0th element in the array.
      */
-    private static final int PERSON_DATA_INDEX_NAME = 0;
-    private static final int PERSON_DATA_INDEX_PHONE = 1;
-    private static final int PERSON_DATA_INDEX_EMAIL = 2;
+    private enum PersonProperty  {NAME, EMAIL, PHONE};
 
     /**
      * The number of data elements for a single person.
@@ -181,14 +179,15 @@ public class AddressBook {
     /**
      * List of all persons in the address book.
      */
-    private static final ArrayList<String[]> ALL_PERSONS = new ArrayList<>();
+    private static final ArrayLIst<HashMap<PersonProperty, String>> ALL_PERSONS = new ArrayList<>();
 
     /**
      * Stores the most recent list of persons shown to the user as a result of a user command.
      * This is a subset of the full list. Deleting persons in the pull list does not delete
      * those persons from this list.
      */
-    private static ArrayList<String[]> latestPersonListingView = getAllPersonsInAddressBook(); // initial view is of all
+    private static ArrayList<HashMap<PersonProperty, String>>
+            latestPersonListingView = getAllPersonsInAddressBook(); // initial view is of all
 
     /**
      * The path to the file used for storing person data.
@@ -417,7 +416,7 @@ private static String getMessageForInvalidCommandInput(String userCommand, Strin
      */
     private static String executeAddPerson(String commandArgs) {
         // try decoding a person from the raw args
-        final Optional<String[]> decodeResult = decodePersonFromString(commandArgs);
+        final Optional<HashMap<PersonProperty, String>> decodeResult = decodePersonFromString(commandArgs);
 
         // checks if args are valid (decode result will not be present if the person is invalid)
         if (!decodeResult.isPresent()) {
@@ -425,7 +424,7 @@ private static String executeAddPerson(String commandArgs) {
         }
 
         // add the person as specified
-        final String[] personToAdd = decodeResult.get();
+        final HashMap<PersonProperty, String> personToAdd = decodeResult.get();
         addPersonToAddressBook(personToAdd);
         return getMessageForSuccessfulAddPerson(personToAdd);
     }
@@ -437,7 +436,7 @@ private static String executeAddPerson(String commandArgs) {
      * @param addedPerson person who was successfully added
      * @return successful add person feedback message
      */
-    private static String getMessageForSuccessfulAddPerson(String[] addedPerson) {
+    private static String getMessageForSuccessfulAddPerson(HashMap<PersonProperty, String> addedPerson) {
         return String.format(MESSAGE_ADDED,
                 getNameFromPerson(addedPerson), getPhoneFromPerson(addedPerson), getEmailFromPerson(addedPerson));
     }
@@ -451,7 +450,7 @@ private static String getMessageForSuccessfulAddPerson(String[] addedPerson) {
      */
     private static String executeFindPersons(String commandArgs) {
         final Set<String> keywords = extractKeywordsFromFindPersonArgs(commandArgs);
-        final ArrayList<String[]> personsFound = getPersonsWithNameContainingAnyKeyword(keywords);
+        final ArrayList<HashMap<PersonProperty, String>> personsFound = getPersonsWithNameContainingAnyKeyword(keywords);
         showToUser(personsFound);
         return getMessageForPersonsDisplayedSummary(personsFound);
     }
@@ -462,7 +461,7 @@ private static String executeFindPersons(String commandArgs) {
      * @param personsDisplayed used to generate summary
      * @return summary message for persons displayed
      */
-    private static String getMessageForPersonsDisplayedSummary(ArrayList<String[]> personsDisplayed) {
+    private static String getMessageForPersonsDisplayedSummary(ArrayList<HashMap<PersonProperty, String>> personsDisplayed) {
         return String.format(MESSAGE_PERSONS_FOUND_OVERVIEW, personsDisplayed.size());
     }
 
@@ -482,9 +481,9 @@ private static Set<String> extractKeywordsFromFindPersonArgs(String findPersonCo
      * @param keywords for searching
      * @return list of persons in full model with name containing some of the keywords
      */
-    private static ArrayList<String[]> getPersonsWithNameContainingAnyKeyword(Collection<String> keywords) {
-        final ArrayList<String[]> matchedPersons = new ArrayList<>();
-        for (String[] person : getAllPersonsInAddressBook()) {
+    private static ArrayList<HashMap<PersonProperty, String>> getPersonsWithNameContainingAnyKeyword(Collection<String> keywords) {
+        final ArrayList<HashMap<PersonProperty, String>> matchedPersons = new ArrayList<>();
+        for (HashMap<PersonProperty, String> person : getAllPersonsInAddressBook()) {
             final Set<String> wordsInName = new HashSet<>(splitByWhitespace(getNameFromPerson(person)));
             if (!Collections.disjoint(wordsInName, keywords)) {
                 matchedPersons.add(person);
@@ -507,7 +506,7 @@ private static String executeDeletePerson(String commandArgs) {
         if (!isDisplayIndexValidForLastPersonListingView(targetVisibleIndex)) {
             return MESSAGE_INVALID_PERSON_DISPLAYED_INDEX;
         }
-        final String[] targetInModel = getPersonByLastVisibleIndex(targetVisibleIndex);
+        final HashMap<PersonProperty, String> targetInModel = getPersonByLastVisibleIndex(targetVisibleIndex);
         return deletePersonFromAddressBook(targetInModel) ? getMessageForSuccessfulDelete(targetInModel) // success
                                                           : MESSAGE_PERSON_NOT_IN_ADDRESSBOOK; // not found
     }
@@ -554,7 +553,7 @@ private static boolean isDisplayIndexValidForLastPersonListingView(int index) {
      * @param deletedPerson successfully deleted
      * @return successful delete person feedback message
      */
-    private static String getMessageForSuccessfulDelete(String[] deletedPerson) {
+    private static String getMessageForSuccessfulDelete(HashMap<PersonProperty, String> deletedPerson) {
         return String.format(MESSAGE_DELETE_PERSON_SUCCESS, getMessageForFormattedPersonData(deletedPerson));
     }
 
@@ -574,7 +573,7 @@ private static String executeClearAddressBook() {
      * @return feedback display message for the operation result
      */
     private static String executeListAllPersonsInAddressBook() {
-        ArrayList<String[]> toBeDisplayed = getAllPersonsInAddressBook();
+        ArrayList<HashMap<PersonProperty, String>> toBeDisplayed = getAllPersonsInAddressBook();
         showToUser(toBeDisplayed);
         return getMessageForPersonsDisplayedSummary(toBeDisplayed);
     }
@@ -629,7 +628,7 @@ private static void showToUser(String... message) {
      * The list will be indexed, starting from 1.
      *
      */
-    private static void showToUser(ArrayList<String[]> persons) {
+    private static void showToUser(ArrayList<HashMap<PersonProperty, String>> persons) {
         String listAsString = getDisplayString(persons);
         showToUser(listAsString);
         updateLatestViewedPersonListing(persons);
@@ -638,10 +637,10 @@ private static void showToUser(ArrayList<String[]> persons) {
     /**
      * Returns the display string representation of the list of persons.
      */
-    private static String getDisplayString(ArrayList<String[]> persons) {
+    private static String getDisplayString(ArrayList<HashMap<PersonProperty, String>> persons) {
         final StringBuilder messageAccumulator = new StringBuilder();
         for (int i = 0; i < persons.size(); i++) {
-            final String[] person = persons.get(i);
+            final HashMap<PersonProperty, String> person = persons.get(i);
             final int displayIndex = i + DISPLAYED_INDEX_OFFSET;
             messageAccumulator.append('\t')
                               .append(getIndexedPersonListElementMessage(displayIndex, person))
@@ -657,7 +656,7 @@ private static String getDisplayString(ArrayList<String[]> persons) {
      * @param person to show
      * @return formatted listing message with index
      */
-    private static String getIndexedPersonListElementMessage(int visibleIndex, String[] person) {
+    private static String getIndexedPersonListElementMessage(int visibleIndex, HashMap<PersonProperty, String> person) {
         return String.format(MESSAGE_DISPLAY_LIST_ELEMENT_INDEX, visibleIndex) + getMessageForFormattedPersonData(person);
     }
 
@@ -667,7 +666,7 @@ private static String getIndexedPersonListElementMessage(int visibleIndex, Strin
      * @param person to show
      * @return formatted message showing internal state
      */
-    private static String getMessageForFormattedPersonData(String[] person) {
+    private static String getMessageForFormattedPersonData(HashMap<PersonProperty, String> person) {
         return String.format(MESSAGE_DISPLAY_PERSON_DATA,
                 getNameFromPerson(person), getPhoneFromPerson(person), getEmailFromPerson(person));
     }
@@ -677,7 +676,7 @@ private static String getMessageForFormattedPersonData(String[] person) {
      *
      * @param newListing the new listing of persons
      */
-    private static void updateLatestViewedPersonListing(ArrayList<String[]> newListing) {
+    private static void updateLatestViewedPersonListing(ArrayList<HashMap<PersonProperty, String>> newListing) {
         // clone to insulate from future changes to arg list
         latestPersonListingView = new ArrayList<>(newListing);
     }
@@ -688,7 +687,7 @@ private static void updateLatestViewedPersonListing(ArrayList<String[]> newListi
      * @param lastVisibleIndex displayed index from last shown person listing
      * @return the actual person object in the last shown person listing
      */
-    private static String[] getPersonByLastVisibleIndex(int lastVisibleIndex) {
+    private static HashMap<PersonProperty, String> getPersonByLastVisibleIndex(int lastVisibleIndex) {
        return latestPersonListingView.get(lastVisibleIndex - DISPLAYED_INDEX_OFFSET);
     }
 
@@ -728,8 +727,9 @@ private static void createFileIfMissing(String filePath) {
      * @param filePath file to load from
      * @return the list of decoded persons
      */
-    private static ArrayList<String[]> loadPersonsFromFile(String filePath) {
-        final Optional<ArrayList<String[]>> successfullyDecoded = decodePersonsFromStrings(getLinesInFile(filePath));
+    private static ArrayList<HashMap<PersonProperty, String>> loadPersonsFromFile(String filePath) {
+        final Optional<ArrayList<HashMap<PersonProperty, String>>>
+                successfullyDecoded = decodePersonsFromStrings(getLinesInFile(filePath));
         if (!successfullyDecoded.isPresent()) {
             showToUser(MESSAGE_INVALID_STORAGE_FILE_CONTENT);
             exitProgram();
@@ -760,7 +760,7 @@ private static ArrayList<String> getLinesInFile(String filePath) {
      *
      * @param filePath file for saving
      */
-    private static void savePersonsToFile(ArrayList<String[]> persons, String filePath) {
+    private static void savePersonsToFile(ArrayList<HashMap<PersonProperty, String>> persons, String filePath) {
         final ArrayList<String> linesToWrite = encodePersonsToStrings(persons);
         try {
             Files.write(Paths.get(storageFilePath), linesToWrite);
@@ -782,7 +782,7 @@ private static void savePersonsToFile(ArrayList<String[]> persons, String filePa
      *
      * @param person to add
      */
-    private static void addPersonToAddressBook(String[] person) {
+    private static void addPersonToAddressBook(HashMap<PersonProperty, String> person) {
         ALL_PERSONS.add(person);
         savePersonsToFile(getAllPersonsInAddressBook(), storageFilePath);
     }
@@ -793,7 +793,7 @@ private static void addPersonToAddressBook(String[] person) {
      * @param exactPerson the actual person inside the address book (exactPerson == the person to delete in the full list)
      * @return true if the given person was found and deleted in the model
      */
-    private static boolean deletePersonFromAddressBook(String[] exactPerson) {
+    private static boolean deletePersonFromAddressBook(HashMap<PersonProperty, String> exactPerson) {
         final boolean changed = ALL_PERSONS.remove(exactPerson);
         if (changed) {
             savePersonsToFile(getAllPersonsInAddressBook(), storageFilePath);
@@ -804,7 +804,7 @@ private static boolean deletePersonFromAddressBook(String[] exactPerson) {
     /**
      * Returns all persons in the address book
      */
-    private static ArrayList<String[]> getAllPersonsInAddressBook() {
+    private static ArrayList<HashMap<PersonProperty, String>> getAllPersonsInAddressBook() {
         return ALL_PERSONS;
     }
 
@@ -821,7 +821,7 @@ private static void clearAddressBook() {
      *
      * @param persons list of persons to initialise the model with
      */
-    private static void initialiseAddressBookModel(ArrayList<String[]> persons) {
+    private static void initialiseAddressBookModel(ArrayList<HashMap<PersonProperty, String>> persons) {
         ALL_PERSONS.clear();
         ALL_PERSONS.addAll(persons);
     }
@@ -838,8 +838,8 @@ private static void initialiseAddressBookModel(ArrayList<String[]> persons) {
      *
      * @param person whose name you want
      */
-    private static String getNameFromPerson(String[] person) {
-        return person[PERSON_DATA_INDEX_NAME];
+    private static String getNameFromPerson(HashMap<PersonProperty, String> person) {
+        return person.get(PersonProperty.NAME);
     }
 
     /**
@@ -847,8 +847,8 @@ private static String getNameFromPerson(String[] person) {
      *
      * @param person whose phone number you want
      */
-    private static String getPhoneFromPerson(String[] person) {
-        return person[PERSON_DATA_INDEX_PHONE];
+    private static String getPhoneFromPerson(HashMap<PersonProperty, String> person) {
+        return person.get(PersonProperty.PHONE);
     }
 
     /**
@@ -856,8 +856,8 @@ private static String getPhoneFromPerson(String[] person) {
      *
      * @param person whose email you want
      */
-    private static String getEmailFromPerson(String[] person) {
-        return person[PERSON_DATA_INDEX_EMAIL];
+    private static String getEmailFromPerson(HashMap<PersonProperty, String> person) {
+        return person.get(PersonProperty.EMAIL);
     }
 
     /**
@@ -868,11 +868,11 @@ private static String getEmailFromPerson(String[] person) {
      * @param email without data prefix
      * @return constructed person
      */
-    private static String[] makePersonFromData(String name, String phone, String email) {
-        final String[] person = new String[PERSON_DATA_COUNT];
-        person[PERSON_DATA_INDEX_NAME] = name;
-        person[PERSON_DATA_INDEX_PHONE] = phone;
-        person[PERSON_DATA_INDEX_EMAIL] = email;
+    private static HashMap<PersonProperty, String> makePersonFromData(String name, String phone, String email) {
+        final HashMap<PersonProperty, String> person = new HashMap<PersonProperty, String>();
+        person.put(PersonProperty.NAME, name);
+        person.put(PersonProperty.PHONE, phone);
+        person.put(PersonProperty.EMAIL, email);
         return person;
     }
 
@@ -882,7 +882,7 @@ private static String[] makePersonFromData(String name, String phone, String ema
      * @param person to be encoded
      * @return encoded string
      */
-    private static String encodePersonToString(String[] person) {
+    private static String encodePersonToString(HashMap<PersonProperty, String> person) {
         return String.format(PERSON_STRING_REPRESENTATION,
                 getNameFromPerson(person), getPhoneFromPerson(person), getEmailFromPerson(person));
     }
@@ -893,9 +893,9 @@ private static String encodePersonToString(String[] person) {
      * @param persons to be encoded
      * @return encoded strings
      */
-    private static ArrayList<String> encodePersonsToStrings(ArrayList<String[]> persons) {
+    private static ArrayList<String> encodePersonsToStrings(ArrayList<HashMap<PersonProperty, String>> persons) {
         final ArrayList<String> encoded = new ArrayList<>();
-        for (String[] person : persons) {
+        for (HashMap<PersonProperty, String> person : persons) {
             encoded.add(encodePersonToString(person));
         }
         return encoded;
@@ -915,12 +915,12 @@ private static ArrayList<String> encodePersonsToStrings(ArrayList<String[]> pers
      * @return if cannot decode: empty Optional
      *         else: Optional containing decoded person
      */
-    private static Optional<String[]> decodePersonFromString(String encoded) {
+    private static Optional<HashMap<PersonProperty, String>> decodePersonFromString(String encoded) {
         // check that we can extract the parts of a person from the encoded string
         if (!isPersonDataExtractableFrom(encoded)) {
             return Optional.empty();
         }
-        final String[] decodedPerson = makePersonFromData(
+        final HashMap<PersonProperty, String> decodedPerson = makePersonFromData(
                 extractNameFromPersonString(encoded),
                 extractPhoneFromPersonString(encoded),
                 extractEmailFromPersonString(encoded)
@@ -936,10 +936,10 @@ private static Optional<String[]> decodePersonFromString(String encoded) {
      * @return if cannot decode any: empty Optional
      *         else: Optional containing decoded persons
      */
-    private static Optional<ArrayList<String[]>> decodePersonsFromStrings(ArrayList<String> encodedPersons) {
-        final ArrayList<String[]> decodedPersons = new ArrayList<>();
+    private static Optional<ArrayList<HashMap<PersonProperty, String>>> decodePersonsFromStrings(ArrayList<String> encodedPersons) {
+        final ArrayList<HashMap<PersonProperty, String>> decodedPersons = new ArrayList<>();
         for (String encodedPerson : encodedPersons) {
-            final Optional<String[]> decodedPerson = decodePersonFromString(encodedPerson);
+            final Optional<HashMap<PersonProperty, String>> decodedPerson = decodePersonFromString(encodedPerson);
             if (!decodedPerson.isPresent()) {
                 return Optional.empty();
             }
@@ -1028,10 +1028,10 @@ private static String extractEmailFromPersonString(String encoded) {
      *
      * @param person String array representing the person (used in internal data)
      */
-    private static boolean isPersonDataValid(String[] person) {
-        return isPersonNameValid(person[PERSON_DATA_INDEX_NAME])
-                && isPersonPhoneValid(person[PERSON_DATA_INDEX_PHONE])
-                && isPersonEmailValid(person[PERSON_DATA_INDEX_EMAIL]);
+    private static boolean isPersonDataValid(HashMap<PersonProperty, String>[] person) {
+        return isPersonNameValid(person.get(PersonProperty.NAME))
+                && isPersonPhoneValid(person.get(PersonProperty.PHONE))
+                && isPersonEmailValid(person.get(PersonProperty.EMAIL));
     }
 
     /*
diff --git a/test/addressbook.txt b/test/addressbook.txt
new file mode 100644
index 00000000..e69de29b