From 873404b640d4179bb8ab5897ea76d9bc65cbc710 Mon Sep 17 00:00:00 2001
From: J2ObjC Team <j2objc-copybara@google.com>
Date: Tue, 26 May 2026 17:24:03 -0700
Subject: [PATCH] Fix AbstractMap assumptions about the atomicity of field
 assignments in thread safe subclasses.

PiperOrigin-RevId: 921776258
---
 .../ojluni/src/main/java/java/util/AbstractMap.java    | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/AbstractMap.java b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/AbstractMap.java
index 3f4ab5448a..301da30e6e 100644
--- a/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/AbstractMap.java
+++ b/jre_emul/android/platform/libcore/ojluni/src/main/java/java/util/AbstractMap.java
@@ -331,8 +331,14 @@ public void clear() {
      * }
      *}</pre>
      */
-    transient Set<K>        keySet;
-    transient Collection<V> values;
+
+    /**
+     * J2ObjC: Despite the discussion above, no field race is safe in J2ObjC because
+     * field access is not atomic in J2ObjC, so mark these volatile so the abstract
+     * implementation is always safe.
+     */
+    transient volatile Set<K>        keySet;
+    transient volatile Collection<V> values;
 
     /**
      * {@inheritDoc}