The video explains the concept of Optionals in Java, containers that may or may not have a value. Optionals are used as return types in methods where null might be returned. Methodology:
- Optionals are used to inform users about the possibility of a value not existing.
- Use `Optional.ofNullable` to place a value in an Optional.
- Utilize `isPresent` to verify the existence of a value before calling `get`.
- Use `orElse` to set a default value if the Optional is empty.
- Use `orElseGet` with a lambda supplier function for a default value.
- Avoid using `get` directly to prevent exceptions; check `isPresent` first.
- Use `map` to change the contents of an Optional and extract specific values.
- Optionals are preferable as return types rather than method parameters.
Notable Quotes
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01:34
— « What exactly is an optional? All an optional is is a container that either has something in it or doesn't.
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03:58
— « This is the way you had to handle this type of situation for a long time in java. This whole situation is where optionals come in.
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04:44
— « So basically now what our method will do is if it finds a cat with that name in the database it will put that cat in the optional box and return it, and if it doesn't find anything it will just return the empty box.
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12:10
— « API note: The preferred alternative to this method is or else throw.
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14:45
— « So it is certainly technically possible to have an optional as a method parameter. »