equals-hashcode: equals/hashCode contract demos, missing hashCode and constant-hash costs, mutable keys, records, JPA entity id trap, 13 contract tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b66uwsWr9B1ouyrzUh
2026-11-12 20:08:35 +05:30
parent 319697c345
commit 682b7b067c
22 changed files with 692 additions and 0 deletions
@@ -0,0 +1,14 @@
+before: get = 100, contains = true
+
+after acc.owner = "ankur":
+map.get(acc)             = null
+set.contains(acc)        = false
+map.containsKey(acc)     = false
+map.size()               = 1
+iteration still sees it  = [Account(ankur)]
+map.remove(acc)          = null
+map.size() after remove  = 1
+
+set.add(acc) again -> size = 2 [Account(ankur), Account(ankur)]  (one object, two entries)
+
+immutable key: map.get("asha") = 1