This article explores three important Java concepts: Optional.of(null), ifPresentOrElse, and reference counting garbage collection. It explains how Optional.of(null) can lead to NullPointerException and demonstrates proper usage of Optional to handle null values safely. The guide also covers ifPresentOrElse, a method introduced in Java 9, to simplify conditional actions on non-null values. Additionally, the article delves into reference counting, a garbage collection technique used to manage memory by tracking object references. This comprehensive overview will help Java developers write cleaner, more efficient code.