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 } --- EOF ---