Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

unmodifiable collection

A collection whose elements can be read but not added, removed or replaced.

Made by List.of, Set.of, Map.of and copyOf; mutators throw UnsupportedOperationException, nulls and duplicates in of are rejected. Not immutable unless its elements are.

Examples

  • List.of(1, 2).add(3) throws UnsupportedOperationException.

See also

unmodifiable list immutable collection view
Read the full section →