Java Null Safety FAQs

Question 1

Why is @Nullable forbidden for method return types?

Accepted Answer

The skill enforces the use of Optional<T> for return types instead of @Nullable because Optional explicitly forces the caller to handle the empty case, preventing accidental NullPointerExceptions.

Question 2

What is unique about the package-info.java syntax?

Accepted Answer

According to the Java Language Specification, in package-info.java, imports must come AFTER the package declaration and its annotations, which is the reverse of standard Java class files.

Question 3

Why does this skill prefer @NullMarked in package-info.java?

Accepted Answer

Using @NullMarked at the package level establishes a 'non-null by default' contract for all classes within that package, significantly reducing annotation noise and making the code safer.

Question 4

Does this skill require specific dependencies?

Accepted Answer

Yes, your project must include the 'org.jspecify:jspecify' dependency to use the @NullMarked and @Nullable annotations supported by this skill.

Question 5

Can I use this skill to migrate existing Java code?

Accepted Answer

Absolutely. The skill includes a specific migration strategy for existing codebases, including adding annotations to packages and refactoring public APIs to follow null-safe patterns.

Java Null Safety

Key Features

Use Cases

Java Null Safety

Key Features

Use Cases