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package com.home;

import java.util.Optional;

/*

The purpose of the class is to provide a type-level solution for representing optional values instead of null references

*/

public class optionalBasics {

public static void main(String[] args) {

//To create an empty Optional object, we simply need to use its empty() static method:

Optional<String> empty = Optional.empty();

System.out.println(empty.isPresent());

String name = "baeldung";

Optional<String> opt = Optional.of(name);

System.out.println(opt.isPresent());

//By doing this, if we pass in a null reference, it doesn't throw an exception

//but rather returns an empty Optional object:

String names = null;//"baeldung";

Optional<String> opts = Optional.ofNullable(names);

System.out.println(opts.isPresent());

//3 way

if (name != null) {

System.out.println(name.length());

}

Optional<String> opt1 = Optional.of("baeldung");

opt1.ifPresent(name11 -> System.out.println(name11.length()));

//The orElse() method is used to retrieve the value wrapped inside an Optional instance. It takes one parameter,

// which acts as a default value. The orElse() method returns the wrapped value if it's present,

// and its argument otherwise:

String nullName = null;

System.out.println(Optional.ofNullable(nullName).orElse("john"));

String nullNames = null;

System.out.println(Optional.ofNullable(nullNames).orElseGet(() -> "john"));

//////orElse with a function

String text = null;

String defaultText = Optional.ofNullable(text).orElse(getMyDefault());

System.out.println(defaultText);

//defaultText = Optional.ofNullable(text).orElseGet(this::getMyDefault);

}

public static String getMyDefault() {

System.out.println("Getting Default Value");

return "Default Value";

}

/*

false

true

false

8

8

john

john

Getting Default Value

Default Value

*/

}