Modular CLI Address Book

A Java 17 command-line application for managing and persistently storing contacts using a modular, layered architecture.

The project focuses on object-oriented domain modeling, separation of concerns, defensive input handling, file-based persistence, and automated testing.

Features

• Automatically loads saved contacts at application startup
• Add, view, edit, delete, and search contacts
• Search by name, address, phone number, or email
• Support multiple addresses, phone numbers, and email addresses per contact
• Support standard and custom labels for contact information
• Persist contacts to structured text storage
• Configure the application data directory with an environment variable
• Skip malformed persisted records while continuing to load valid contacts
• Protect internal contact collections from uncontrolled external modification
• Centralize console input through a single input utility
• Validate menu selections and other interactive choices
• Unit and filesystem-based integration testing with JUnit 5

Architecture

The application separates responsibilities across focused packages.

Application

app.Main is the application entry point. It creates the address book manager and starts the interactive CLI session.

Manager

AddressBookManager coordinates contact storage, loading, saving, and mutation while protecting its internal contact collection from direct modification.

Domain Model

Contact represents an address book entry and aggregates:

• Address
• PhoneNumber
• EmailAddress

Searchable domain objects implement the shared Matchable interface.

Contact uses defensive copies and unmodifiable collection views to protect its internal state. Explicit addition and replacement methods provide controlled modification of contact data.

Input and Editing

The input package handles interactive CLI workflows, including contact creation, display, search, and deletion.

The editor package handles modifications to existing contact information.

Console input is centralized through PromptUtils, which owns the application's single Scanner for System.in.

Display

ContactDisplayFormatter provides structured formatting of contact information for console output.

Persistence

The io package provides file-based persistence through:

• FileLoader
• FileSaver
• FileParser<T>
• LineParser<T>
• AppPaths

Parsing and object construction are separated so persistence logic remains reusable and testable.

Data Persistence

Contacts are stored in:

data/address_book.csv

Each line represents one contact using semicolon-delimited components.

Example:

James,,Stevens;Home:123 Maple St|Chicago|IL|60601;Mobile:312-555-0101;Personal:james@example.com

The application skips blank lines and malformed records during loading so one invalid record does not prevent valid contacts from being recovered.

Error Handling

The CLI handles invalid interactive selections without terminating the application. Yes/no prompts require recognized responses, invalid numeric selections are rejected safely, and active operations can be cancelled with exit without terminating the application.

Persisted domain tokens are validated during parsing. Malformed records are skipped while valid records continue to load.

File I/O failures are handled by the application session rather than silently ignored.

Testing

The project uses JUnit 5 for unit and filesystem-based integration testing.

The current automated suite contains 25 tests covering:

• Contact name formatting
• Case-insensitive and partial search behavior
• Phone-number search independent of display formatting
• Domain parsing and serialization
• Malformed domain tokens
• Contact serialization round trips
• Defensive collection copying
• Unmodifiable collection views
• Controlled addition and replacement of contact data
• File parsing and blank-line handling
• Recovery from malformed persisted records
• File save/load round trips
• Manager persistence behavior
• Contact removal
• Protection of the manager's internal contact collection

Filesystem tests use JUnit temporary directories so application data is not modified during testing.

Run the test suite with:

mvn test

Getting Started

Prerequisites

• Java 17 or later
• Maven 3.8 or later

Run with Maven

mvn -q exec:java

The application will create the data directory when necessary, load address_book.csv when present, and start the interactive CLI session.

Build the Runnable JAR

mvn clean package

Then run:

java -jar target/modular-cli-address-book-1.0.0-SNAPSHOT.jar

Configuration

By default, application data is stored in:

./data

Override the base data directory with the APP_DATA_DIR environment variable:

export APP_DATA_DIR=/path/to/data
mvn -q exec:java

This also allows application data to be isolated from the repository when desired.

Project Structure

src/
├── main/
│   └── java/
│       ├── app/
│       └── addressbook/
│           ├── display/
│           ├── editor/
│           ├── input/
│           ├── io/
│           ├── manager/
│           └── model/
└── test/
    └── java/
        └── addressbook/
            ├── io/
            ├── manager/
            └── model/

What This Project Demonstrates

• Java 17
• Maven
• Object-oriented domain modeling
• Layered application design
• Separation of concerns
• Encapsulation and defensive copying
• Generic parsing abstractions
• File-based persistence
• Defensive input and persistence handling
• Environment-based configuration
• JUnit 5 unit testing
• Filesystem integration testing
• Runnable JAR packaging

License

This project is licensed under the MIT License. See the LICENSE file for details.