Java Language
- Getting started with Java Language
- Top 10 Java Errors with Solutions
- Awesome Book
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- Optional
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- Lazily provide a default value using a Supplier
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- Return default value if Optional is empty
- Run code only if there is a value present
- Throw an exception, if there is no value
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- XOM - XML Object Model
Java Language Optional
Introduction
Optional is a container object which may or may not contain a non-null value. If a value is present, isPresent() will return true and get() will return the value.
Additional methods that depend on the presence of the contained value are provided, such as orElse(), which returns a default value if value not present, and ifPresent() which executes a block of code if the value is present.
Syntax
- Optional.empty() // Creates an empty Optional instance.
- Optional.of(value) // Returns an Optional with the specified non-null value. A NullPointerException will be thrown if the passed value is null.
- Optional.ofNullable(value) // Returns an Optional with the specified value that may be null.
Optional Related Examples
- Filter
- FlatMap
- Lazily provide a default value using a Supplier
- Map
- Return default value if Optional is empty
- Run code only if there is a value present
- Throw an exception, if there is no value
- Using Optional containers for primitive number types
