Why is this an issue?
Optional acts as a container object that may or may not contain a non-null value. It is introduced in Java 8 to help avoid
NullPointerException. It provides methods to check if a value is present and retrieve the value if it is present.
Optional is used instead of null values to make the code more readable and avoid potential errors.
It is a bad practice to use null with Optional because it is unclear whether a value is present or not, leading to
confusion and potential NullPointerException errors.
How to fix it
There are a few ways to fix this issue:
- Avoid returning
null from a method whose return type is Optional.
- Remove the null-check of an
Optional and use Optional methods instead, like isPresent() or
ifPresent().
Code examples
Noncompliant code example
public void doSomething () {
Optional<String> optional = getOptional();
if (optional != null) { // Noncompliant
// do something with optional...
}
Optional<String> text = null; // Noncompliant, a variable whose type is Optional should never itself be null
// ...
}
@Nullable // Noncompliant
public Optional<String> getOptional() {
// ...
return null; // Noncompliant
}
Compliant solution
public void doSomething () {
Optional<String> optional = getOptional();
optional.ifPresent(
// do something with optional...
);
Optional<String> text = Optional.empty();
// ...
}
public Optional<String> getOptional() {
// ...
return Optional.empty();
}
Resources
Documentation
Articles & blog posts
