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JavaIntermediate#collections
JavaIntermediate#fundamentals
What is autoboxing and unboxing?
Automatic conversion between primitives and wrapper types (int ↔ Integer). Convenient but can cause subtle bugs (NPE on unboxing null, performance overhead in loops).
Example
Integer boxed = 10; // autoboxing int primitive = boxed; // unboxing Integer n = null; int x = n; // throws NullPointerException at unboxing