Difference between `Optional.orElse()` and `Optional.orElseGet()`

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Take these two scenarios:

Optional<Foo> opt = ...
Foo x = opt.orElse( new Foo() );
Foo y = opt.orElseGet( Foo::new );

If opt doesn’t contain a value, the two are indeed equivalent. But if opt does contain a value, how many Foo objects will be created?

P.s.: of course in this example the difference probably wouldn’t be measurable, but if you have to obtain your default value from a remote web service for example, or from a database, it suddenly becomes very important.

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