Java Optional and Empty Collections: Stop Returning null | Effective Java L53

Lecture 53 of the Effective Java Masterclass by Engineer X · Part 7: Methods. In this lecture • A food app's order-again card that crashes for a brand-new customer because a method returned null • Return empty collections and zero-length arrays, never null, and why the performance argument fails • Shared immutable empties (Collections.emptyList, a static empty array) and toArray without presizing • Optional for a single value that may be missing: of, ofNullable, empty, and never a null Optional • orElse vs orElseGet (eager vs lazy), orElseThrow, map/filter/flatMap, or, ifPresentOrElse, Optional::stream • Where Optional doesn't belong: containers, map values, fields; OptionalInt for primitives; its cost • Modern Java: List.of() is null-hostile, toArray(String[]::new), requireNonNullElse, Optional.isEmpty and orElseThrow() Chapters 0:00 A new customer crashes the app 0:35 Empty, not null 1:17 But what about allocation? 2:13 Optional for one maybe-value 3:12 Using an Optional 4:58 Where Optional doesn't belong 5:37 Modern Java: sharp edges 6:34 In the interview 7:21 Recap and quiz Follows the topics of Effective Java, 3rd edition, by Joshua Bloch (Item 54: Return empty collections or arrays, not nulls, Item 55: Return optionals judiciously). Every explanation, example and line of code in this lecture is original. Previous lecture: L052 Java Overloading vs Overriding: Why list.remove(1) Removes the Wrong Element Next lecture: L054 How to Write Javadoc in Java: @param, @return, @throws and the Summary Line #Java #EffectiveJava #JavaInterview #SeniorJavaDeveloper #JavaBestPractices #EngineerX #JavaOptional #NullSafety #JavaCollections #EffectiveJava