Boxing unboxing (ARCH602)

Key dotnet.performance.boxing-unboxing · Severity info · Category performance

Converting value types to object incurs heap allocation and copying overhead.

Incorrect

ArrayList list = new ArrayList();
list.Add(42);          // boxing
int x = (int)list[0];  // unboxing

Correct

List<int> list = new List<int>();
list.Add(42);
int x = list[0];

Fix

Use generic collections and methods to eliminate boxing.