GraphQL Java Development Guidelines

This skill provides code style conventions and pull request review guidelines for GraphQL Java implementation projects, based on the official graphql-java/graphql-java repository standards.

Instructions

When working on GraphQL Java projects, follow these guidelines:

Code Style and Conventions

1. **Import Style**

- NEVER use fully qualified names for Java, Kotlin, or Groovy classes

- Always add proper imports at the top of the file

- NEVER use wildcard imports (e.g., `import java.util.*`)

- Import items one by one explicitly

- Configure your IDE to disable wildcard imports

2. **Code Formatting**

- Follow the code style defined in `graphql-java-code-style.xml`

- Apply consistent formatting across all Java, Kotlin, and Groovy files

- Maintain consistency with existing codebase patterns

Pull Request Review Guidelines

3. **Testing Requirements**

- Every new functionality MUST include corresponding tests

- Every bug fix MUST include a test that verifies the fix

- Tests ensure code works correctly in the future and prevents regressions

4. **Performance Improvements**

- If the PR includes performance improvements, check in a JMH (Java Microbenchmark Harness) test

- JMH tests verify performance claims objectively

- Performance tests will be run on isolated performance environments for verification

5. **Breaking Changes**

- Clearly flag any breaking changes to public APIs in the PR description

- Document breaking changes so they can be called out in release notes

- Consider deprecation paths before introducing breaking changes

Usage Examples

**When adding a new feature:**

```java

// ✅ Good: Explicit imports, new feature with test

import graphql.schema.GraphQLSchema;

import graphql.schema.GraphQLObjectType;

import graphql.schema.GraphQLFieldDefinition;

public class NewFeature {

// Implementation with corresponding test in NewFeatureTest.java

}

```

**When fixing a bug:**

```java

// ✅ Good: Bug fix with regression test

import graphql.execution.ExecutionContext;

import graphql.language.Field;

public class BugFix {

// Fix implementation with test in BugFixTest.java proving it works

}

```

**Performance improvement:**

```java

// ✅ Good: Performance optimization with JMH benchmark

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

@BenchmarkMode(Mode.Throughput)

public class PerformanceBenchmark {

@Benchmark

public void measurePerformance() {

// Benchmark code

}

}

```

Constraints