src/java.base/share/classes/java/util/ArrayList.java

*** 107,116 ****
--- 107,117 ----
   * @since   1.2
   */
  public class ArrayList<E> extends AbstractList<E>
          implements List<E>, RandomAccess, Cloneable, java.io.Serializable
  {
+     @java.io.Serial
      private static final long serialVersionUID = 8683452581122892189L;
  
      /**
       * Default initial capacity.
       */
*** 847,856 ****
--- 848,858 ----
       * @throws java.io.IOException if an I/O error occurs
       * @serialData The length of the array backing the {@code ArrayList}
       *             instance is emitted (int), followed by all of its elements
       *             (each an {@code Object}) in the proper order.
       */
+     @java.io.Serial
      private void writeObject(java.io.ObjectOutputStream s)
          throws java.io.IOException {
          // Write out element count, and any hidden stuff
          int expectedModCount = modCount;
          s.defaultWriteObject();
*** 874,883 ****
--- 876,886 ----
       * @param s the stream
       * @throws ClassNotFoundException if the class of a serialized object
       *         could not be found
       * @throws java.io.IOException if an I/O error occurs
       */
+     @java.io.Serial
      private void readObject(java.io.ObjectInputStream s)
          throws java.io.IOException, ClassNotFoundException {
  
          // Read in size, and any hidden stuff
          s.defaultReadObject();