How to Apply Multiple Consumers to an Optional in Java?

How can I apply multiple Consumers to an Optional in Java using the fluent API?

Optional.ofNullable(key)
    .map(Person::get)
    .ifPresent(this::printName)
    .ifPresent(this::printAddress); // not compiling, because ifPresent is void

In Java, Optional serves as a container that may or may not contain a non-null value. This is particularly useful for avoiding null pointer exceptions. However, when you want to perform multiple operations on an Optional value using Consumers, you'll need a different approach since ifPresent does not allow for chaining multiple actions directly due to its void return type.

// Combine Consumers with 'andThen'
Consumer<Person> printPersonDetails = this::printName.andThen(this::printAddress);

Optional.ofNullable(key)
    .map(Person::get)
    .ifPresent(printPersonDetails);

Causes

• The ifPresent method executes a Consumer action if a value is present, but it does not return any value itself, making it impossible to chain multiple ifPresent calls.

Solutions

• You can combine multiple Consumers into one by using the 'andThen' method.
• Alternatively, you can utilize the 'flatMap' method to return a new Optional, which can contain additional logic before further consumer applications.
• Another option is to create a custom method that applies multiple actions in sequence.

Mistake: Trying to chain multiple ifPresent calls

Solution: Use a combined Consumer instead with a method reference or lambda that calls multiple actions.

Mistake: Not handling the case where the Optional may be empty

Solution: Always consider the empty case when applying operations to an Optional.