Java's Optional should be used correctly to avoid increasing code complexity. 1. Do not wrap null with Optional.ofNullable() should be used to deal with values ??that may be null; 2. Avoid using Optional in entity classes or collections, because it increases memory overhead and serialization is prone to problems; 3. Use orElse and orElseGet correctly, and use orElseGet first when the default value is high at a high cost; 4. Try to avoid calling get() directly, and it is recommended to use it in combination with ifPresent() or map()/filter() to improve security. Optional is designed to explicitly express “may not exist” situations and to facilitate handling of such logic. Proper use can improve code readability and robustness, while misuse increases maintenance costs.
Java Optional is a container class introduced to reduce null pointer exceptions, but if used improperly, it will make the code complicated or even misleading logic. It is not a universal solution, but it can indeed improve the readability and robustness of the code if used properly.
1. Do not wrap null with Optional
Many people mistakenly think that Optional.of(null) is a good practice, but in fact this is wrong. The correct way to do this is to use Optional.ofNullable() to handle values ??that may be null:
Optional<String> optional = Optional.ofNullable(someString);
If you are sure that a value is not empty, use of() directly; if you are not sure, use of ofNullable() only. Don't abuse Optional to wrap an object that is originally null. This is not only meaningless, but also easily hides problems.
2. Avoid using Optional in entity classes or collections
Some people like to declare Optional in entity class fields, like this:
public class User {
private Optional<String> name;
}This way of writing seems "elegant", but it actually brings several problems:
- Increase memory overhead (each Optional instance takes up extra space)
- Problems may arise when serializing/deserializing (different frameworks handle inconsistently)
- When using getter, you still need to determine whether it is present. It is better to directly judge null.
Similarly, it is not recommended to put Optional in a collection, such as List<Optional<String>> , such structures are difficult to operate and prone to errors.
3. Use orElse and orElseGet correctly
These two methods look similar, but may differ in performance. See example:
// Always create a default object regardless of whether there is a value optional.orElse(createDefault()); // Only when needed will optional.orElseGet(() -> createDefault());
So when the default value you provide is expensive to create, you should prioritize orElseGet . Otherwise you can choose one at will.
In addition, if you just want to throw exceptions instead of providing default values, you can use orElseThrow() directly, which is concise and clear.
4. Try to avoid get() unless you have judged isPresent()
Many NullPointerExceptions are actually called get() and do not determine whether the value exists. Therefore, the recommended method is to use it in combination with ifPresent() or map() and filter() :
optional.map(String::toUpperCase).ifPresent(System.out::println);
This will make the logic smoother and avoid omissions caused by manual judgment.
Of course, sometimes you are indeed sure that the value exists, so you can also use get() with confidence, but make sure that there is a logical guarantee before.
Basically that's it. Optional is not something that must be used, nor can it be installed anywhere. The key is to understand its original design intention: to allow developers to express the situation that "may not exist" more clearly and to prompt us to deal with it . If used correctly, the code will be clearer; if used wrong, it will increase maintenance costs.
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