JSON File Database

A Java CLI application to add, view, and update user records, persisted locally in a JSON file using the Jackson library.

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Requirements

• Java JDK 8 or higher
• Maven (to resolve dependencies)

No additional setup needed — data is stored locally in a JSON file.

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How to Run

1. Clone the repository
2. Add Jackson Databind to your pom.xml:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.17.1</version>
</dependency>

3. Run Main.java and follow the prompts

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What It Does

• Add a new user (ID, name, age, occupation, language)
• Look up a user by ID
• Update fields of an existing user (skip any field to leave it unchanged)
• Persists data to src/main/java/database.json automatically
• Handles missing database file by creating it on first run
• Safely handles lookups for non-existent IDs

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Pros

• Zero external database setup — just a flat JSON file
• Human-readable storage, easy to inspect or edit manually
• TreeMap keeps records sorted by ID automatically
• Lightweight with minimal dependencies
• Runs on any device with Java and Maven installed

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Limitations

• No delete — there is no way to remove a user
• No input validation — entering a string where an integer is expected will crash
• No duplicate ID check — adding a user with an existing ID silently overwrites it
• Not thread-safe — concurrent access would corrupt the JSON file
• Flat schema — the UserRecord model is rigid; adding new fields requires code changes
• Hardcoded file path — database location is fixed to src/main/java/database.json

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Possible Improvements

• Add a delete-by-ID option
• Validate input types before parsing (especially age)
• Check for ID conflicts before inserting and prompt accordingly
• Add search by name instead of just ID
• Make the database file path configurable
• Replace the flat JSON file with SQLite for more robust storage as the project grows