Smart Task Scheduler

Simple task scheduler built in pure Java using ScheduledExecutorService.

The application loads scheduled tasks from a JSON file and executes them based on their configured start time.

How it works

• Tasks are loaded from ~/.smart-task-scheduler/tasks.json
• Each task must define a start timestamp
• Optional end timestamp defines the execution validity window
• Tasks are scheduled using ScheduledExecutorService

Running the application

./mvnw clean package
java -jar target/smart-task-scheduler.jar

Task JSON format

[
  {
    "name": "Daily report",
    "start": "2026-02-01T10:00:00Z",
    "end": "2026-02-01T10:05:00Z",
    "priority": "MEDIUM"
  }
]

• start is required and must follow ISO-8601 format with timezone
• end is optional and defines task expiration

Technical decisions

• Uses Instant to represent absolute time
• Custom Gson TypeAdapter for Java Time support
• Defensive validation for invalid or expired tasks
• No external scheduler frameworks (Quartz, Spring)

Limitations

• Tasks are not persisted after execution
• Scheduler state is lost when the JVM stops