Project: ABC Business Contacts

ABC Business Contacts is a free desktop contact management application that helps the user to manage a large collection of contacts conveniently and keep track of appointments. The user can store contacts as well as other information and retrieve them efficiently with the help of ABC.
The user interacts with it using a Command Line Interface(CLI), and it has a Graphic User Interface(GUI) created with JavaFX. It is written in Java, and has about 6 kLoC.

Code contributed: [Functional code] [Test code]

Enhancement Added: find Command Reworked

External behavior

Start of Extract [from: User Guide]

Locating persons by keywords: find

Command Name: find
Shorthand Alias: f
Function : Displays a filtered list of persons whose specified fields contain any of the given keywords
Format: find [n/KEYWORD…​] [p/KEYWORD…​] [e/KEYWORD…​] [a/KEYWORD…​] [t/KEYWORD…​]

There must be at least one argument

  • The search is case insensitive e.g hans will match Hans

  • Only exact words will be matched e.g. Han will not match Hans

  • Persons matching at least one search term in the specified field will be returned e.g. find n/Hans Bo will return Hans Gruber, Bo Yang

  • Wildcard symbols * and ? are allowed in the parameters where * matches any non-space string and ? matches any non-space unit-length symbol

  • The search is done on the most recent listing. Successive find commands make the list smaller

If you want to find a person named John Watson:

  1. Type in
    >> find n/john
    (See Figure 4.4.1)
    find1
    Figure 4.4.1

  2. Press Enter and you should see a list of persons having the name john
    (See Figure 4.4.2)
    find2
    Figure 4.4.2

Here are some other ways you can use find:

  • >> find t/friends family p/88887777
    Lists any person having tags friends or family or whose phone number is 88887777.

  • >> f e/*@example.com
    Lists any person whose email domain is example.com.

  • >> find n/steph?n
    Lists persons whose name is stephan or stephen.

End of Extract

Key Feature 1: Works on all fields

Justification

The new find command now works on all fields, i.e. Name, Phone Number, Email, Address and Tag. For example, the user can find a contact by phone numbers.
This allows the user to locate specific contacts efficiently using all available information on top of Name.

Key Feature 2: Allows wildcard symbols

Justification

Wildcard symbols * and ? are allowed in the parameters to match unknown symbols.
The use of wildcard symbols allows fuzzy search. It enables the user to search even if he forgets certain details.
The use of wildcard symbols also allows the user to search for a group of contacts sharing something similar. For example, the user can use *@example.com to search for contacts whose emails share the same domain.

Key Feature 3: Filters the displayed list

Justification

The find command filters the displayed list of contacts. Contacts not shown in the most recent listing would NOT show up in the result of a find command. Therefore, successive find commands would make the list smaller and smaller.
By filtering the displayed list, the user can narrow down the list to locate a specific contact without exact information or find a group of contacts sharing multiple similar properties.

Implementation

Start of Extract [from: Developer Guide]

Filtering mechanism in find

Basic mechanism

The list of persons displayed is filtered by a [Predicate] when the method updateFilteredPersonList(predicate) from the Model interface is invoked.

The relevant methods in the Model interface are as follows:

public interface Model {

  ...

  /** Returns the predicate of the current filtered person list */
  Predicate<? super ReadOnlyPerson> getPersonListPredicate();

  /** Updates the filter of the filtered person list to filter by the given {@code predicate}.*/
  void updateFilteredPersonList(Predicate<ReadOnlyPerson> predicate);

}

When updateFilteredPersonList(predicate) is invoked, every Person in ABC is evaluated against the predicate. A Person is added to the displayed list if predicate.test(person) is evaluated to be TRUE. Therefore, all Person instances that fulfill the conditions specified in predicate are displayed.

Filtering the displayed list

Note that all Person instances in the displayed list satisfy a Predicate currentPredicate. Given a new Predicate newPredicate, filtering the displayed list of contacts is equivalent to selecting Person instances that satisfy both currentPredicate and newPredicate. From Figure 3.4.2.1, it can also be viewed as the intersection of two lists of Person objects, each satisfying one of the two predicates respectively.

venn diagram

Figure 3.4.2.1 : Venn Diagram for Filtering

Implementation

The actual implementation of filtering the displayed list involves three steps.

  1. Invoke getPersonListPredicate() provided in the Model interface to get the currentPredicate.

  2. Use [Predicate.and()] to generated the logical AND of the two predicates.

  3. Update the list using the predicate generated in step 2.

For more detail, refer to the sequence diagram(Figure 3.4.3.1) below.

FindCommandSequenceDiagram

Figure 3.4.3.1 : Sequence Diagram for Find

Design consideration

The design for filtering the displayed list applies the [Open/Close Principle].

  • By providing a new extension of getPersonListPredicate() in the Model interface, the new feature is enabled.

  • By making use of the logical AND of two predicates, the list can be filtered without modification of the fundamental filtering mechanism.

End of Extract

Enhancement Added: Auto-Completion Suggestion

External behavior

Start of Extract [from: User Guide]

  • Suggestions will pop up for partial words keyed in. Press TAB to auto-complete using the first suggestion or press ↑↓ arrows and Enter to choose the suggestion.

End of Extract

Suggestions are also generated based on the context of what the user has keyed in. If the user is typing a command word, a list of valid command words would be generated. If the user is keying in tags, a list of valid tags from the stored contact data would be generated.

Justification

Auto-Completion allows users to type less. Moreover, since all suggestions are generated from the stored data, it can reduce the chance of mistyping. For example, if the user wants to find a contact by a very long name, the name would show up as a suggestion when the user type in the first few letters. On the other hand, if the user needs to type the name out in full, there is a higher chance for him to make mistakes.

Enhancement Added: resize Command

External behavior

Start of Extract [from: User Guide]

Resizing the main window : resize

Command Name: resize
Shorthand Alias: rs
Function: Resizes the main window to the specified width and height in pixels
Format: resize WIDTH HEIGHT

Restriction on WIDTH and HEIGHT: 300 < = WIDTH < = width of the screen display, 230 < = HEIGHT < = height of the screen display
You CANNOT undo a resize command

If you want to resize your main window to 1280 * 720:

  1. Type in
    >> resize 1280 720
    (See Figure 4.23.1)
    resize
    Figure 4.23.1

  2. Press Enter and the main window will be resized to 1280 * 720

End of Extract

Justification

The resize command allows the user to enlarge/shrink the size of the main window conveniently using CLI so that he can view more contacts or make space in the screen for other applications.

Enhancement Proposed: A More Powerful find Command

  • The user can choose to search from all contacts instead of the displayed ones using an argument -a which stands for all. For example, find -a t/friends would search for ALL contacts that are tagged with friends.

  • The user can choose to search for contacts that satisfy all conditions using an argument -s which stands for strict. For example, find -s n/John t/friends would search for contacts that match BOTH the name John the tag friends.

  • The user can choose to filter away unwanted contacts from the displayed list using an argument -u which stands for unwanted. For instance, find -u t/friends would filter AWAY contacts tagged with friends.

Enhancement Proposed: Rank Auto-Completion Suggestions by Occurrence

If a certain keyword is frequently used, it would show up first in the suggestion menu.

Other contributions

  • Discovered a bug that causes the app to crash and provided a solution. (Issue #137)

  • Discovered bugs during acceptance testing. (Issues #116, #117, #118)

  • Proposed wildcard symbol feature for reuse. (Issue #132)

  • Fixed a bug on undo/redo. (Pull Request #172)