Skip to main content

requireNullMarked

Category: Rules Reference
Scope: Classes, Interfaces, Enums, Annotations
Purpose: Ensures that classes are annotated with @NullMarked to define a clear default nullness context.

What does it check?​

The requireNullMarked rule verifies that classes (and other types like interfaces and enums) are properly annotated with @NullMarked, unless explicitly excluded.

Without @NullMarked, types may have unspecified nullness, which can lead to ambiguity or bugs.

Why is it important?​

  • Enforces explicit nullness context at the class level.
  • Helps avoid missing nullability specifications on fields, methods, and parameters.

Examples​

❌ Invalid Example: Class without @NullMarked​

package com.example;

public class UserProfile {

    private String username;
    private String email;
}

Problem detected:

[ERROR] com.example.UserProfile: Missing @NullMarked annotation on the class.

✅ Valid Example: Class with @NullMarked​

package com.example;

import org.jspecify.annotations.NullMarked;

@NullMarked
public class UserProfile {

    private String username;
    private String email;
}

How to configure it?​

You can enable the requireNullMarked rule by adding it to your plugin configuration:


<configuration>
    <rules>
        <requireNullMarked/>
    </rules>
</configuration>

Optional parameters:

ParameterTypeDefaultDescription
exclusionsFileString(none)Path to a text file listing classes to exclude, see Exclusions File Format

When to enable?​

Recommended for:

  • New projects starting with JSpecify annotations.
  • Projects migrating to explicit nullness declarations.
  • Teams that want to enforce consistent annotation practices during development and in CI/CD pipelines.

Limitations​

  • Only verifies the presence of @NullMarked.
  • The rule does not require @NullMarked on package-info.java — it only focuses on types (classes, interfaces, enums, etc.).