1 /*
  2  * Copyright (c) 2003, 2026, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  */
 23 
 24 /*
 25  * @test
 26  * @bug     4809442 6366832 4974878 6372554 4890211 6483125
 27  * @summary Basic test for Collections.reverseOrder
 28  * @author  Josh Bloch, Martin Buchholz
 29  * @library /test/lib
 30  */
 31 
 32 import jdk.test.lib.valueclass.VClass;
 33 import java.io.ByteArrayInputStream;
 34 import java.io.ByteArrayOutputStream;
 35 import java.io.IOException;
 36 import java.io.InputStream;
 37 import java.io.ObjectInputStream;
 38 import java.io.ObjectOutputStream;
 39 import java.util.ArrayList;
 40 import java.util.Arrays;
 41 import java.util.Collections;
 42 import java.util.Comparator;
 43 import java.util.LinkedList;
 44 import java.util.List;
 45 
 46 public class ReverseOrder2 {
 47     static final int N = 100;
 48 
 49     static void realMain(String[] args) throws Throwable {
 50         check(Collections.reverseOrder()
 51               == Collections.reverseOrder(null));
 52 
 53         check(Collections.reverseOrder()
 54               == reincarnate(Collections.reverseOrder()));
 55 
 56         check(Collections.reverseOrder(Collections.reverseOrder(cmp))
 57               == cmp);
 58 
 59         equal(Collections.reverseOrder(cmp),
 60               Collections.reverseOrder(cmp));
 61 
 62         equal(Collections.reverseOrder(cmp).hashCode(),
 63               Collections.reverseOrder(cmp).hashCode());
 64 
 65         check(Collections.reverseOrder(cmp).hashCode() !=
 66               cmp.hashCode());
 67 
 68         test(new ArrayList<String>());
 69         test(new LinkedList<String>());
 70         test2(new ArrayList<Integer>());
 71         test2(new LinkedList<Integer>());
 72 
 73         List<VClass> values = new ArrayList<>(Arrays.asList(new VClass(0, new int[] { 0 }), new VClass(1, new int[] { 1 }), new VClass(2, new int[] { 2 })));
 74         Collections.shuffle(values);
 75         Collections.sort(values, Collections.reverseOrder());
 76         if (!values.equals(Arrays.asList(new VClass(2, new int[] { 2 }), new VClass(1, new int[] { 1 }), new VClass(0, new int[] { 0 }))))
 77             throw new RuntimeException("value reverseOrder2 failed");
 78     }
 79 
 80     static void test(List<String> list) {
 81         for (int i = 0; i < N; i++)
 82             list.add(String.valueOf(i));
 83         Collections.shuffle(list);
 84         Collections.sort(list, Collections.reverseOrder(cmp));
 85         equal(list, golden);
 86     }
 87 
 88     private static Comparator<String> cmp = new Comparator<>() {
 89         public int compare(String s1, String s2) {
 90             int i1 = Integer.parseInt(s1);
 91             int i2 = Integer.parseInt(s2);
 92             return (i1 < i2 ? Integer.MIN_VALUE : (i1 == i2 ? 0 : 1));
 93         }
 94     };
 95 
 96     private static final List<String> golden = new ArrayList<>(N);
 97     static {
 98         for (int i = N-1; i >= 0; i--)
 99             golden.add(String.valueOf(i));
100     }
101 
102     static void test2(List<Integer> list) {
103         for (int i = 0; i < N; i++)
104             list.add(i);
105         Collections.shuffle(list);
106         Collections.sort(list, Collections.reverseOrder(null));
107         equal(list, golden2);
108     }
109 
110     private static final List<Integer> golden2 = new ArrayList<>(N);
111     static {
112         for (int i = N-1; i >= 0; i--)
113             golden2.add(i);
114     }
115 
116     //--------------------- Infrastructure ---------------------------
117     static volatile int passed = 0, failed = 0;
118     static void pass() {passed++;}
119     static void fail() {failed++; Thread.dumpStack();}
120     static void fail(String msg) {System.out.println(msg); fail();}
121     static void unexpected(Throwable t) {failed++; t.printStackTrace();}
122     static void check(boolean cond) {if (cond) pass(); else fail();}
123     static void equal(Object x, Object y) {
124         if (x == null ? y == null : x.equals(y)) pass();
125         else fail(x + " not equal to " + y);}
126     public static void main(String[] args) throws Throwable {
127         try {realMain(args);} catch (Throwable t) {unexpected(t);}
128         System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
129         if (failed > 0) throw new AssertionError("Some tests failed");}
130     static byte[] serializedForm(Object obj) {
131         try {
132             ByteArrayOutputStream baos = new ByteArrayOutputStream();
133             new ObjectOutputStream(baos).writeObject(obj);
134             return baos.toByteArray();
135         } catch (IOException e) {throw new RuntimeException(e);}}
136     static Object readObject(byte[] bytes)
137         throws IOException, ClassNotFoundException {
138         InputStream is = new ByteArrayInputStream(bytes);
139         return new ObjectInputStream(is).readObject();}
140     @SuppressWarnings("unchecked")
141     static <T> T reincarnate(T obj) {
142         try {return (T) readObject(serializedForm(obj));}
143         catch (Exception e) {throw new RuntimeException(e);}}
144 }
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