Java 27 and 26: runnable demos and captured output for every JEP, plus version lanes

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3

lanes/src/UnsafeWarning.java

@@ -0,0 +1,21 @@
+import java.lang.reflect.Field;
+import sun.misc.Unsafe;
+
+/**
+ * "sun.misc.Unsafe memory methods deprecated for removal": JEP 471 (23) deprecated them, JEP 498 (24) makes the first
+ * call print a warning at run time. This allocates and frees 8 bytes off-heap and shows what the JVM says.
+ * Chapter: docs/14-lanes-21-to-25.md
+ */
+public class UnsafeWarning {
+    @SuppressWarnings("removal")
+    public static void main(String[] args) throws Exception {
+        System.out.println("java.version = " + System.getProperty("java.version"));
+        Field f = Unsafe.class.getDeclaredField("theUnsafe");
+        f.setAccessible(true);
+        Unsafe u = (Unsafe) f.get(null);
+        long addr = u.allocateMemory(8);
+        u.putLong(addr, 42L);
+        System.out.println("read back: " + u.getLong(addr));
+        u.freeMemory(addr);
+    }
+}