Java Project Skill

Name: project-java
Rating: 76
Author: pagopa

When to use

•Services, handlers, controllers, utilities, modules.
•Refactoring or extending existing Java components.

Mandatory rules

•Add concise purpose JavaDoc for new/changed core classes.
•Use emoji logs for key runtime transitions when logging is touched.
•Prefer early return and guard clauses.
•Keep code readable and avoid over-engineering.
•Add unit tests for testable logic.

Minimal class example

java

/** Purpose: Resolve user by id with input validation. */
public final class UserService {
    public String resolveUserId(String userId) {
        if (userId == null || userId.isBlank()) {
            throw new IllegalArgumentException("❌ userId is required");
        }
        return userId.trim();
    }
}

Test stack

•JUnit 5.
•BDD-like naming with @DisplayName and given_when_then.

Minimal test example

java

import static org.junit.jupiter.api.Assertions.assertThrows;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

class UserServiceTest {
    @Test
    @DisplayName("given blank userId when resolving then throws")
    void givenBlankUserId_whenResolving_thenThrows() {
        var service = new UserService();
        assertThrows(IllegalArgumentException.class, () -> service.resolveUserId(" "));
    }
}