test/jdk/java/util/Collections/Ser.java

*** 1,7 ***
  /*
!  * Copyright (c) 1999, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ---
  /*
!  * Copyright (c) 1999, 2026, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

*** 24,21 ***
--- 24,39 ---
  /*
   * @test
   * @bug 4190323
   * @summary EMPTY_SET, EMPTY_LIST, and the collections returned by
   *          nCopies and singleton were spec'd to be serializable, but weren't.
+  * @library /test/lib
   */
  
+ import jdk.test.lib.valueclass.AsValueClass;
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
+ import java.io.Serializable;
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  
  public class Ser {
+ 
+     @AsValueClass
+     static final class SerV implements Serializable {
+         int x;
+         SerV(int x) { this.x = x; }
+         public boolean equals(Object o) { return o instanceof SerV v && x == v.x; }
+         public int hashCode() { return x; }
+         private Object writeReplace() { return new SerProxy(x); }
+         private static class SerProxy implements Serializable {
+             int x;
+             SerProxy(int x) { this.x = x; }
+             private Object readResolve() { return new SerV(x); }
+         }
+     }
+ 
      public static void main(String[] args) throws Exception {
  
          try {
              ByteArrayOutputStream bos = new ByteArrayOutputStream();
              ObjectOutputStream out = new ObjectOutputStream(bos);

*** 94,7 ***
--- 112,35 ---
              if (!gumbies.equals(in.readObject()))
                  throw new RuntimeException("nCopies Ser/Deser failure.");
          } catch (Exception e) {
              throw new RuntimeException("Failed to serialize nCopies:" + e);
          }
+ 
+         try {
+             ByteArrayOutputStream bos = new ByteArrayOutputStream();
+             ObjectOutputStream out = new ObjectOutputStream(bos);
+             Set<SerV> one = Collections.singleton(new SerV(1));
+             out.writeObject(one);
+             out.flush();
+             ObjectInputStream in = new ObjectInputStream(
+                     new ByteArrayInputStream(bos.toByteArray()));
+             if (!one.equals(in.readObject()))
+                 throw new RuntimeException("value singleton Ser/Deser failure");
+         } catch (Exception e) {
+             throw new RuntimeException("Failed to serialize value singleton: " + e);
+         }
+ 
+         try {
+             ByteArrayOutputStream bos = new ByteArrayOutputStream();
+             ObjectOutputStream out = new ObjectOutputStream(bos);
+             List<SerV> many = Collections.nCopies(5, new SerV(2));
+             out.writeObject(many);
+             out.flush();
+             ObjectInputStream in = new ObjectInputStream(
+                     new ByteArrayInputStream(bos.toByteArray()));
+             if (!many.equals(in.readObject()))
+                 throw new RuntimeException("value nCopies Ser/Deser failure");
+         } catch (Exception e) {
+             throw new RuntimeException("Failed to serialize value nCopies: " + e);
+         }
      }
  }