Optional
summary
Java 8’s Optional is a small (<20 methods) return-type box that replaces null results and is often misused; guidelines include never use null for Optional, avoid Optional.get unless proven present, prefer map/flatMap/orElse/ifPresent, and don’t convert nullable fields or method parameters into Optionals. Java 9 adds Optional.stream and ifPresentOrElse/or; Optional stays non‑serializable to preserve future value‑type plans (Project Valhalla). Antipatterns: nested Optionals, Optionals in collections, clever stream hacks that hurt readability and cause memory/GC overhead.
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chapters (20)
- 0:00Introduction
- 0:40API without Optional
- 3:00Optional
- 5:56Find
- 7:27Get
- 8:15IsPresent
- 9:36Optional Get
- 10:37Optional Or Else
- 12:01Optional Map
- 13:57Chaining Methods
- 14:33Filter Method
- 16:42If Present
- 18:12Static Methods
- 19:26New Methods
- 24:10Examples
- 31:50Optional Methods
- 35:53Optional History
- 37:12Optional Serializable
- 39:09Optional and Field
- 42:29Summary Conclusion
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