Which @NotNull Java annotation should I use?

 

In Java, the @NotNull annotation is typically used to indicate that a particular parameter, field, or return value of a method should not be null. However, it's important to note that there is no standard @NotNull annotation in the Java standard library. Instead, various libraries and frameworks provide their own @NotNull annotations. Two commonly used ones are:

1. javax.validation.constraints.NotNull (from Java Validation API): This annotation is part of the Java Validation API (JSR 380) and is often used for validation purposes. It can be used to specify that a parameter or field should not be null.

   Example usage:

   java

import javax.validation.constraints.NotNull;

public class MyClass {
    private String name;

    public MyClass(@NotNull String name) {
        this.name = name;
    }

    public void setName(@NotNull String name) {
        this.name = name;
    }

    @NotNull
    public String getName() {
        return name;
    }
}

In this example, we've used @NotNull to indicate that the name parameter in the constructor, the name parameter in the setName method, and the return value of the getName method should not be null.

org.jetbrains.annotations.NotNull (from JetBrains IntelliJ Annotations): This annotation is commonly used in projects developed with JetBrains IntelliJ IDEA, and it's available as part of the IntelliJ Annotations library. It serves a similar purpose to the javax.validation.constraints.NotNull annotation.

Example usage:

java

2. import org.jetbrains.annotations.NotNull;
   
   public class MyClass {
       private String name;
   
       public MyClass(@NotNull String name) {
           this.name = name;
       }
   
       public void setName(@NotNull String name) {
           this.name = name;
       }
   
       @NotNull
       public String getName() {
           return name;
       }
   }
   

   In this example, we've used @NotNull from the JetBrains IntelliJ Annotations library to indicate that the name parameter in the constructor, the name parameter in the setName method, and the return value of the getName method should not be null.

You should choose the @NotNull annotation that aligns with your project's dependencies and coding standards. If you're using a specific framework or library that provides its own @NotNull annotation, it's a good practice to use that one to maintain consistency within your codebase.