1/* 2 * Copyright (c) 2007, 2014, 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 5017904 6356890 8004928 27 * @summary Test empty iterators, enumerations, and collections 28 */ 29 30import static java.util.Collections.*; 31import java.util.*; 32import java.util.concurrent.SynchronousQueue; 33 34public class EmptyIterator { 35 36 void test(String[] args) throws Throwable { 37 testEmptyCollection(emptyList()); 38 testEmptyCollection(emptySet()); 39 testEmptyCollection(new SynchronousQueue<Object>()); 40 testEmptyMap(emptyMap()); 41 42 Hashtable<?,?> emptyTable = new Hashtable<>(); 43 testEmptyEnumeration(emptyTable.keys()); 44 testEmptyEnumeration(emptyTable.elements()); 45 testEmptyIterator(emptyTable.keySet().iterator()); 46 testEmptyIterator(emptyTable.values().iterator()); 47 testEmptyIterator(emptyTable.entrySet().iterator()); 48 49 final Enumeration<EmptyIterator> finalEmptyTyped = emptyEnumeration(); 50 testEmptyEnumeration(finalEmptyTyped); 51 52 final Enumeration<?> finalEmptyAbstract = emptyEnumeration(); 53 testEmptyEnumeration(finalEmptyAbstract); 54 55 testEmptyIterator(emptyIterator()); 56 } 57 58 void testEmptyEnumeration(final Enumeration<?> e) { 59 check(e == emptyEnumeration()); 60 check(!e.hasMoreElements()); 61 THROWS(NoSuchElementException.class, 62 new F(){void f(){ e.nextElement(); }}); 63 } 64 65 void testEmptyIterator(final Iterator<?> it) { 66 check(it == emptyIterator()); 67 check(! it.hasNext()); 68 THROWS(NoSuchElementException.class, 69 new F(){void f(){ it.next(); }}); 70 THROWS(IllegalStateException.class, 71 new F(){void f(){ it.remove(); }}); 72 } 73 74 void testEmptyMap(Map<?,?> m) { 75 check(m == emptyMap()); 76 check(m.entrySet().iterator() == 77 Collections.<Map.Entry<?,?>>emptyIterator()); 78 check(m.values().iterator() == emptyIterator()); 79 check(m.keySet().iterator() == emptyIterator()); 80 equal(m, unmodifiableMap(m)); 81 82 testEmptyCollection(m.keySet()); 83 testEmptyCollection(m.entrySet()); 84 testEmptyCollection(m.values()); 85 } 86 87 void testToArray(final Collection<?> c) { 88 Object[] a = c.toArray(); 89 equal(a.length, 0); 90 equal(a.getClass().getComponentType(), Object.class); 91 THROWS(NullPointerException.class, 92 new F(){void f(){ c.toArray((Object[])null); }}); 93 94 { 95 String[] t = new String[0]; 96 check(c.toArray(t) == t); 97 } 98 99 { 100 String[] t = nCopies(10, "").toArray(new String[0]); 101 check(c.toArray(t) == t); 102 check(t[0] == null); 103 for (int i=1; i<t.length; i++) 104 check(t[i] == ""); 105 } 106 } 107 108 void testEmptyCollection(final Collection<?> c) { 109 testEmptyIterator(c.iterator()); 110 111 check(c.iterator() == emptyIterator()); 112 if (c instanceof List) 113 check(((List<?>)c).listIterator() == emptyListIterator()); 114 115 testToArray(c); 116 } 117 118 //--------------------- Infrastructure --------------------------- 119 volatile int passed = 0, failed = 0; 120 void pass() {passed++;} 121 void fail() {failed++; Thread.dumpStack();} 122 void fail(String msg) {System.err.println(msg); fail();} 123 void unexpected(Throwable t) {failed++; t.printStackTrace();} 124 void check(boolean cond) {if (cond) pass(); else fail();} 125 void equal(Object x, Object y) { 126 if (x == null ? y == null : x.equals(y)) pass(); 127 else fail(x + " not equal to " + y);} 128 public static void main(String[] args) throws Throwable { 129 new EmptyIterator().instanceMain(args);} 130 void instanceMain(String[] args) throws Throwable { 131 try {test(args);} catch (Throwable t) {unexpected(t);} 132 System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed); 133 if (failed > 0) throw new AssertionError("Some tests failed");} 134 abstract class F {abstract void f() throws Throwable;} 135 void THROWS(Class<? extends Throwable> k, F... fs) { 136 for (F f : fs) 137 try {f.f(); fail("Expected " + k.getName() + " not thrown");} 138 catch (Throwable t) { 139 if (k.isAssignableFrom(t.getClass())) pass(); 140 else unexpected(t);}} 141} 142