Add lazy-constants module: LazyConstant (JEP 531) against the holder idiom and double-checked locking

Basics, failure semantics on 26 vs 27, lazy collections, API across 25/26/27, preview-flag traps and a JMH read-path benchmark (jars fetched and sha1-checked, not committed). Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01TF9JWFvJSNm6HVzswzZU5a
2026-09-24 12:27:27 +00:00
parent af44e59e7f
commit 814c32b5ce
25 changed files with 606 additions and 0 deletions
@@ -0,0 +1,26 @@
+$ javac --enable-preview --release 27 src/LazyCollections.java && java --enable-preview LazyCollections     (27+35)
+list created, size 3 (nothing computed yet)
+  computing list element 1
+list.get(1) = v1
+list.get(1) again = v1
+map created, size 3 (nothing computed yet)
+  computing map value for bb
+map.get("bb") = 2
+map.get("bb") again = 2
+set created
+  testing 2
+set.contains(2) = true
+  testing 1
+set.contains(1) = false
+set.contains(9) = false
+  testing 3
+set.size() = 2
+
+$ javac --enable-preview --release 26 src/LazyCollections.java     (26.0.2.1+1)
+src/LazyCollections.java:18: error: cannot find symbol
+        Set<Integer> set = Set.ofLazy(Set.of(1, 2, 3), n -> { System.out.println("  testing " + n); return n > 1; });
+                              ^
+  symbol:   method ofLazy(Set<Integer>,(n)->{ Sys[...] 1; })
+  location: interface Set
+1 error
+exit=1