Which `@NotNull` Annotation Should I Use in My Java Code?

Choosing the Optimal @NotNull Annotation for Your Java Code

Introduction

In Java development, nullability annotations play a crucial role in enhancing code readability and leveraging static code analysis tools to prevent NullPointerExceptions. However, the abundance of available annotations can be overwhelming, leading to confusion about which one to choose.

Comparative Analysis

To guide your decision, here is a comparison of several commonly used @NotNull annotations:

• javax.validation.constraints.NotNull: Designed for runtime validation, not static analysis.
• edu.umd.cs.findbugs.annotations.NonNull: Used by FindBugs (now deprecated) and its successor SpotBugs.
• javax.annotation.Nonnull: Based on JSR-305, which is inactive but may be supported by FindBugs.
• org.jetbrains.annotations.NotNull: Used by IntelliJ IDEA for static analysis.
• lombok.NonNull: Controls code generation in Project Lombok.
• androidx.annotation.NonNull: Marker annotation available in Android.
• org.eclipse.jdt.annotation.NonNull: Used by Eclipse for static code analysis.

Recommendation

Since JSR-305, which aimed to standardize @NonNull and @Nullable annotations, has been inactive for years, there is no clear consensus. However, a pragmatic approach can be taken:

Syntax

For a clean and concise syntax, it is recommended to use javax.annotation.Nonnull. It is the shortest and aligns with the preferred style of avoiding explicit references to third-party toolkits.

Implementation

While most @NotNull annotations have a trivial implementation, javax.annotation.Nonnull has a longer one. However, it has the advantage of being a runtime annotation, allowing for runtime checks in addition to compile-time ones.

Usage Contexts

Pay attention to the usage contexts supported by different annotations. Some packages, like org.jetbrains.annotations, allow annotations on local variables, while others do not. Consider your specific code and toolchain requirements when selecting the appropriate annotation.

The above is the detailed content of Which `@NotNull` Annotation Should I Use in My Java Code?. For more information, please follow other related articles on the PHP Chinese website!