reflection: Method/Field/MethodHandle/VarHandle demos, module and final-field rules (JEP 500 on JDK 26), JMH call-cost numbers, contract tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b6NtPJHrkan4BXhCAM

reflection/output/04-method-handles.txt

@@ -0,0 +1,31 @@
+$ java -cp target/classes com.ankurm.reflection.MethodHandlesDemo
+
+== 1. Look up once, call many times ==
+twice(21)        = 42
+balance()        = 50
+handle type      = (Account)long
+
+== 2. invokeExact is exact; invoke adapts ==
+invokeExact, wrong return type -> WrongMethodTypeException
+  handle's method type (Account)long but found (Account)Object
+invoke (boxing)  = 50 (Long)
+
+== 3. Handles compose ==
+bindTo(acct)     = 50
+after deposit10  = Account[erin, 60]
+balance as text  = "60"
+
+== 4. Access is checked when you look up, not when you call ==
+findVirtual(private) -> IllegalAccessException
+  no such method: com.ankurm.reflection.Account.secret()String/invokeVirtual
+privateLookupIn      -> secret-of-erin
+privateLookupIn(String) -> IllegalAccessException
+  module java.base does not open java.lang to unnamed module @135fbaa4
+
+== 5. VarHandle: typed, atomic field access ==
+get              = 60
+CAS(60 -> 100)   = true, balance now 100
+CAS(60 -> 200)   = false, balance now 100
+getAndAdd(5)     = was 100, now 105
+set on final field -> UnsupportedOperationException
+array element CAS-able: counts[1] = 7