Java Coding Problems

227. Optional.get() and missing value

So, if we have decided to call Optional.get() to fetch the value wrapped in Optional, then we shouldn't do it as follows:

Optional<Book> book = ...; // this is prone to be empty// Avoid// if "book" is empty then the following code will// throw a java.util.NoSuchElementExceptionBook theBook = book.get();

In other words, before fetching the value via Optional.get(), we need to prove that the value is present. A solution consists of calling isPresent() before calling get(). This way, we add a check that allows us to handle the missing value case:

Optional<Book> book = ...; // this is prone to be empty// Preferif (book.isPresent()) {  Book theBook = book.get();  ... // do something with "theBook"} else { ... ...