1 /*
2 * Copyright (c) 2007, 2011, 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
30 import static java.util.Collections.*;
31 import java.util.*;
32
33 public class EmptyIterator {
34
35 void test(String[] args) throws Throwable {
36 testEmptyCollection(Collections.<Object>emptyList());
37 testEmptyCollection(Collections.<Object>emptySet());
38
39 testEmptyMap(Collections.<Object, Object>emptyMap());
40
41 Hashtable<Object, Object> emptyTable = new Hashtable<Object, Object>();
42 testEmptyEnumeration(emptyTable.keys());
43 testEmptyEnumeration(emptyTable.elements());
44 testEmptyIterator(emptyTable.keySet().iterator());
45 testEmptyIterator(emptyTable.values().iterator());
46 testEmptyIterator(emptyTable.entrySet().iterator());
47
48 final Enumeration<EmptyIterator> finalEmptyTyped =
49 Collections.emptyEnumeration();
50 testEmptyEnumeration(finalEmptyTyped);
51
52 final Enumeration finalEmptyAbstract =
53 Collections.emptyEnumeration();
54 testEmptyEnumeration(finalEmptyAbstract);
55
56 @SuppressWarnings("unchecked") Iterator<?> x =
57 new sun.tools.java.MethodSet()
58 .lookupName(sun.tools.java.Identifier.lookup(""));
59 testEmptyIterator(x);
60 }
61
62 <T> void testEmptyEnumeration(final Enumeration<T> e) {
63 check(e == emptyEnumeration());
64 check(! e.hasMoreElements());
65 THROWS(NoSuchElementException.class,
66 new F(){void f(){ e.nextElement(); }});
67 }
68
69 <T> void testEmptyIterator(final Iterator<T> it) {
70 check(it == emptyIterator());
71 check(! it.hasNext());
72 THROWS(NoSuchElementException.class,
73 new F(){void f(){ it.next(); }});
74 THROWS(IllegalStateException.class,
75 new F(){void f(){ it.remove(); }});
76 }
77
78 void testEmptyMap(Map<Object, Object> m) {
79 check(m == emptyMap());
80 check(m.entrySet().iterator() ==
81 Collections.<Map.Entry<Object,Object>>emptyIterator());
82 check(m.values().iterator() == emptyIterator());
83 check(m.keySet().iterator() == emptyIterator());
84 equal(m, unmodifiableMap(m));
85
86 testEmptyCollection(m.keySet());
87 testEmptyCollection(m.entrySet());
88 testEmptyCollection(m.values());
89 }
90
91 <E> void testToArray(final Collection<E> c) {
92 Object[] a = c.toArray();
93 equal(a.length, 0);
94 equal(a.getClass().getComponentType(), Object.class);
95 THROWS(NullPointerException.class,
96 new F(){void f(){ c.toArray((Object[])null); }});
97
98 {
99 String[] t = new String[0];
100 check(c.toArray(t) == t);
101 }
102
103 {
104 String[] t = nCopies(10, "").toArray(new String[0]);
105 check(c.toArray(t) == t);
106 check(t[0] == null);
107 for (int i=1; i<t.length; i++)
108 check(t[i] == "");
109 }
110 }
111
112 <E> void testEmptyCollection(final Collection<E> c) {
113 testEmptyIterator(c.iterator());
114
115 check(c.iterator() == emptyIterator());
116 if (c instanceof List)
117 check(((List<?>)c).listIterator() == emptyListIterator());
118
119 testToArray(c);
120 }
121
122 //--------------------- Infrastructure ---------------------------
123 volatile int passed = 0, failed = 0;
124 void pass() {passed++;}
125 void fail() {failed++; Thread.dumpStack();}
126 void fail(String msg) {System.err.println(msg); fail();}
127 void unexpected(Throwable t) {failed++; t.printStackTrace();}
128 void check(boolean cond) {if (cond) pass(); else fail();}
129 void equal(Object x, Object y) {
130 if (x == null ? y == null : x.equals(y)) pass();
131 else fail(x + " not equal to " + y);}
132 public static void main(String[] args) throws Throwable {
133 new EmptyIterator().instanceMain(args);}
134 void instanceMain(String[] args) throws Throwable {
135 try {test(args);} catch (Throwable t) {unexpected(t);}
136 System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
137 if (failed > 0) throw new AssertionError("Some tests failed");}
138 abstract class F {abstract void f() throws Throwable;}
139 void THROWS(Class<? extends Throwable> k, F... fs) {
140 for (F f : fs)
141 try {f.f(); fail("Expected " + k.getName() + " not thrown");}
142 catch (Throwable t) {
143 if (k.isAssignableFrom(t.getClass())) pass();
144 else unexpected(t);}}
145 }