1 /*
2 * Copyright (c) 2005, 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 6267846 6275009
27 * @summary Test Collections.nCopies
28 * @author Martin Buchholz
29 * @library /test/lib
30 */
31
32 import jdk.test.lib.valueclass.VClass;
33 import java.util.ArrayList;
34 import java.util.Collections;
35 import java.util.AbstractList;
36 import java.util.List;
37 import java.util.Objects;
38
39 public class NCopies {
40 static volatile int passed = 0, failed = 0;
41
42 static void fail(String msg) {
43 failed++;
44 new AssertionError(msg).printStackTrace();
45 }
46
47 static void pass() {
48 passed++;
49 }
50
51 static void unexpected(Throwable t) {
52 failed++;
53 t.printStackTrace();
54 }
55
56 static void check(boolean condition, String msg) {
57 if (condition)
58 passed++;
59 else
60 fail(msg);
61 }
62
63 static void check(boolean condition) {
64 check(condition, "Assertion failure");
65 }
66
67 private static void checkEmpty(List<String> x) {
68 check(x.isEmpty());
69 check(x.size() == 0);
70 check(x.indexOf("foo") == -1);
71 check(x.lastIndexOf("foo") == -1);
72 check(x.toArray().length == 0);
73 check(x.toArray().getClass() == Object[].class);
74 }
75
76 private static void checkFoos(List<String> x) {
77 check(! x.isEmpty());
78 check(x.indexOf(new String("foo")) == 0);
79 check(x.lastIndexOf(new String("foo")) == x.size()-1);
80 check(x.toArray().length == x.size());
81 check(x.toArray().getClass() == Object[].class);
82 String[] sa = x.toArray(new String[x.size()]);
83 check(sa.getClass() == String[].class);
84 check(sa[0].equals("foo"));
85 check(sa[sa.length-1].equals("foo"));
86 check(x.get(x.size()/2).equals("foo"));
87 checkEmpty(x.subList(x.size()/2, x.size()/2));
88 }
89
90 private static <T> List<T> referenceNCopies(int n, T o) {
91 // A simplest correct implementation of nCopies to compare with the actual optimized implementation
92 return new AbstractList<>() {
93 public int size() { return n; }
94
95 public T get(int index) {
96 Objects.checkIndex(index, n);
97 return o;
98 }
99 };
100 }
101
102 private static void checkHashCode() {
103 int[] sizes = {0, 1, 2, 3, 5, 10, 31, 32, 100, 1000};
104 String[] elements = {null, "non-null"};
105 for (int size : sizes) {
106 for (String element : elements) {
107 int expectedHashCode = referenceNCopies(size, element).hashCode();
108 int actualHashCode = Collections.nCopies(size, element).hashCode();
109 check(expectedHashCode == actualHashCode,
110 "Collections.nCopies(" + size + ", " + element + ").hashCode()");
111 }
112 }
113 }
114
115 private static void checkEquals() {
116 int[][] sizePairs = {{0, 0}, {0, 1}, {1, 0}, {1, 1}, {1, 2}, {2, 1}};
117 String[] elements = {null, "non-null"};
118 for (int[] pair : sizePairs) {
119 for (String element : elements) {
120 boolean equal = pair[0] == pair[1];
121 String msg = "[" + pair[0] + ", " + element + "] <=> [" + pair[1] + ", " + element + "]";
122 check(equal == Collections.nCopies(pair[0], element).equals(Collections.nCopies(pair[1], element)), msg);
123 check(equal == Collections.nCopies(pair[0], element).equals(referenceNCopies(pair[1], element)), msg);
124 check(equal == referenceNCopies(pair[0], element).equals(Collections.nCopies(pair[1], element)), msg);
125 }
126 }
127 List<String> nulls = Collections.nCopies(10, null);
128 List<String> nonNulls = Collections.nCopies(10, "non-null");
129 List<String> nullsButOne = new ArrayList<>(nulls);
130 nullsButOne.set(9, "non-null");
131 List<String> nonNullsButOne = new ArrayList<>(nonNulls);
132 nonNullsButOne.set(9, null);
133 check(!nulls.equals(nonNulls));
134 check(!nulls.equals(nullsButOne));
135 check(!nulls.equals(nonNullsButOne));
136 check(!nonNulls.equals(nonNullsButOne));
137 check(Collections.nCopies(0, null).equals(Collections.nCopies(0, "non-null")));
138 }
139
140 private static void checkReversed() {
141 List<String> copies = Collections.nCopies(10, "content");
142 check(copies.equals(copies.reversed()));
143 List<String> empty = Collections.nCopies(0, "content");
144 check(empty.equals(empty.reversed()));
145 }
146
147 private static void checkValueCopies() {
148 List<VClass> copies = Collections.nCopies(10, new VClass(7, new int[] { 7 }));
149 check(copies.indexOf(new VClass(7, new int[] { 7 })) == 0);
150 check(copies.lastIndexOf(new VClass(7, new int[] { 7 })) == 9);
151 check(copies.equals(referenceNCopies(10, new VClass(7, new int[] { 7 }))));
152 check(copies.hashCode() == referenceNCopies(10, new VClass(7, new int[] { 7 })).hashCode());
153 check(copies.equals(copies.reversed()));
154 }
155
156 public static void main(String[] args) {
157 try {
158 List<String> empty = Collections.nCopies(0, "foo");
159 checkEmpty(empty);
160 checkEmpty(empty.subList(0,0));
161
162 List<String> foos = Collections.nCopies(42, "foo");
163 check(foos.size() == 42);
164 checkFoos(foos.subList(foos.size()/2, foos.size()-1));
165
166 checkHashCode();
167
168 checkEquals();
169
170 checkReversed();
171
172 checkValueCopies();
173
174 } catch (Throwable t) { unexpected(t); }
175
176 System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
177 if (failed > 0) throw new Error("Some tests failed");
178 }
179 }