Java 8 optional class | java optional class interview questions | java 8 interview | okay java

Java 8 optional | optional class | optional class interview questions | java 8 interview | okay java
Java 8 Optional class
Optional.empty()
Optional.of()
Optional.ofNullable()
.isPresent()
.ifPresent()
.get()
.orElse()
.orElseGet()
orElse v/s orElseGet()
.orElseThrow()
.filter()
.map()
.flatMap()
What is optional in java 8 ?
Optional is Final class in Java 8
to handle values as ‘available’ or ‘not available’ instead of checking null values.
What are the different ways to create an optional object
Optional.empty()
Optional.of()
Optional.ofNullable()
Optional.of() v/s Optional.ofNullable()
What is difference b/w Optional.of() and Optional.ofNullable() ?
Optional.of does not handle the "null" value , it gives null pointer exception.
.isPresent()
Boolean function
Returns true if there is a value present, otherwise false.
.get()
If a value is present in this Optional, returns the value, otherwise throws NoSuchElementException.
. ifPresent(consumer)
if a value is present, it invokes the specified consumer with the value, otherwise does nothing.
opStr2.ifPresent(s -> System.out.println(s.toUpperCase()));
. orElseThrow(supplier)
Returns the contained value, if present, otherwise throws an exception to be created by the provided supplier.
// orElseThrow
Optional < Integer > item = Optional.empty();
. filter(predicate)
If a value is present and the value matches a given predicate, it returns an Optional describing the value, otherwise returns an empty Optional.
// Filter - apply a predicate
Optional Integer age = Optional.of(20);
int a = age.filter(n -> n > 18).get();
System.out.println(a);
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[@sreeharikuttuboinaghhthump5824]

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[@kirane5911]

Very useful video. Thanks for good Explanation. Very Easy Explanation so that Those listening can easy understand Both practically and theoretically. Before did not understand internal implementation of optional class. But you made it very carefully understood. Thanks you so much.

[@492832]

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[@okayjava]

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[@mowglishihtzutoy5197]

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[@vitthal_varak108K]

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[@okayjava]

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[@cooldudev78]

I like your other videos . But , In this video Your explanation about or else and or else get is not good at all and you are not explaining the differences . Please when you explain , compare the difference very well. Please take this as a positive feed back to improve the content

[@okayjava]

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