util/Collections/EmptyIterator.java

/*
 * Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 5017904 6356890 8004928
 * @summary Test empty iterators, enumerations, and collections
 */

import static java.util.Collections.*;
import java.util.*;
import java.util.concurrent.SynchronousQueue;

public class EmptyIterator {

    void test(String[] args) throws Throwable {
        testEmptyCollection(emptyList());
        testEmptyCollection(emptySet());
        testEmptyCollection(new SynchronousQueue<Object>());
        testEmptyMap(emptyMap());

        Hashtable<?,?> emptyTable = new Hashtable<>();
        testEmptyEnumeration(emptyTable.keys());
        testEmptyEnumeration(emptyTable.elements());
        testEmptyIterator(emptyTable.keySet().iterator());
        testEmptyIterator(emptyTable.values().iterator());
        testEmptyIterator(emptyTable.entrySet().iterator());

        final Enumeration<EmptyIterator> finalEmptyTyped = emptyEnumeration();
        testEmptyEnumeration(finalEmptyTyped);

        final Enumeration<?> finalEmptyAbstract = emptyEnumeration();
        testEmptyEnumeration(finalEmptyAbstract);

        testEmptyIterator(emptyIterator());
    }

    void testEmptyEnumeration(final Enumeration<?> e) {
        check(e == emptyEnumeration());
        check(!e.hasMoreElements());
        THROWS(NoSuchElementException.class,
               new F(){void f(){ e.nextElement(); }});
    }

    void testEmptyIterator(final Iterator<?> it) {
        check(it == emptyIterator());
        check(! it.hasNext());
        THROWS(NoSuchElementException.class,
               new F(){void f(){ it.next(); }});
        THROWS(IllegalStateException.class,
               new F(){void f(){ it.remove(); }});
    }

    void testEmptyMap(Map<?,?> m) {
        check(m == emptyMap());
        check(m.entrySet().iterator() ==
              Collections.<Map.Entry<?,?>>emptyIterator());
        check(m.values().iterator() == emptyIterator());
        check(m.keySet().iterator() == emptyIterator());
        equal(m, unmodifiableMap(m));

        testEmptyCollection(m.keySet());
        testEmptyCollection(m.entrySet());
        testEmptyCollection(m.values());
    }

    void testToArray(final Collection<?> c) {
        Object[] a = c.toArray();
        equal(a.length, 0);
        equal(a.getClass().getComponentType(), Object.class);
        THROWS(NullPointerException.class,
               new F(){void f(){ c.toArray((Object[])null); }});

        {
            String[] t = new String[0];
            check(c.toArray(t) == t);
        }

        {
            String[] t = nCopies(10, "").toArray(new String[0]);
            check(c.toArray(t) == t);
            check(t[0] == null);
            for (int i=1; i<t.length; i++)
                check(t[i] == "");
        }
    }

    void testEmptyCollection(final Collection<?> c) {
        testEmptyIterator(c.iterator());

        check(c.iterator() == emptyIterator());
        if (c instanceof List)
            check(((List<?>)c).listIterator() == emptyListIterator());

        testToArray(c);
    }

    //--------------------- Infrastructure ---------------------------
    volatile int passed = 0, failed = 0;
    void pass() {passed++;}
    void fail() {failed++; Thread.dumpStack();}
    void fail(String msg) {System.err.println(msg); fail();}
    void unexpected(Throwable t) {failed++; t.printStackTrace();}
    void check(boolean cond) {if (cond) pass(); else fail();}
    void equal(Object x, Object y) {
        if (x == null ? y == null : x.equals(y)) pass();
        else fail(x + " not equal to " + y);}
    public static void main(String[] args) throws Throwable {
        new EmptyIterator().instanceMain(args);}
    void instanceMain(String[] args) throws Throwable {
        try {test(args);} catch (Throwable t) {unexpected(t);}
        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
        if (failed > 0) throw new AssertionError("Some tests failed");}
    abstract class F {abstract void f() throws Throwable;}
    void THROWS(Class<? extends Throwable> k, F... fs) {
        for (F f : fs)
            try {f.f(); fail("Expected " + k.getName() + " not thrown");}
            catch (Throwable t) {
                if (k.isAssignableFrom(t.getClass())) pass();
                else unexpected(t);}}
}
Revision:	1.6
Committed:	Tue Sep 15 16:59:14 2015 UTC (8 years, 8 months ago) by jsr166
Branch:	MAIN
Changes since 1.5:	+31 -27 lines
Log Message:	merge upstream changes
#	User	Rev	Content
1	jsr166	1.1	/*
2	jsr166	1.6	* Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.
3	jsr166	1.1	* 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	jsr166	1.2	* 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	jsr166	1.1	*/
23
24			/*
25			* @test
26	jsr166	1.6	* @bug 5017904 6356890 8004928
27	jsr166	1.1	* @summary Test empty iterators, enumerations, and collections
28			*/
29
30	jsr166	1.6	import static java.util.Collections.*;
31	jsr166	1.1	import java.util.*;
32	jsr166	1.6	import java.util.concurrent.SynchronousQueue;
33	jsr166	1.1
34			public class EmptyIterator {
35
36			void test(String[] args) throws Throwable {
37	jsr166	1.6	testEmptyCollection(emptyList());
38			testEmptyCollection(emptySet());
39			testEmptyCollection(new SynchronousQueue<Object>());
40			testEmptyMap(emptyMap());
41	jsr166	1.1
42	jsr166	1.6	Hashtable<?,?> emptyTable = new Hashtable<>();
43	jsr166	1.1	testEmptyEnumeration(emptyTable.keys());
44			testEmptyEnumeration(emptyTable.elements());
45			testEmptyIterator(emptyTable.keySet().iterator());
46			testEmptyIterator(emptyTable.values().iterator());
47			testEmptyIterator(emptyTable.entrySet().iterator());
48
49	jsr166	1.6	final Enumeration<EmptyIterator> finalEmptyTyped = emptyEnumeration();
50			testEmptyEnumeration(finalEmptyTyped);
51
52			final Enumeration<?> finalEmptyAbstract = emptyEnumeration();
53			testEmptyEnumeration(finalEmptyAbstract);
54
55			testEmptyIterator(emptyIterator());
56	jsr166	1.1	}
57
58	jsr166	1.6	void testEmptyEnumeration(final Enumeration<?> e) {
59			check(e == emptyEnumeration());
60			check(!e.hasMoreElements());
61	jsr166	1.1	THROWS(NoSuchElementException.class,
62			new F(){void f(){ e.nextElement(); }});
63			}
64
65	jsr166	1.6	void testEmptyIterator(final Iterator<?> it) {
66			check(it == emptyIterator());
67	jsr166	1.1	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	jsr166	1.6	void testEmptyMap(Map<?,?> m) {
75			check(m == emptyMap());
76	jsr166	1.1	check(m.entrySet().iterator() ==
77	jsr166	1.6	Collections.<Map.Entry<?,?>>emptyIterator());
78	jsr166	1.1	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	jsr166	1.6	void testToArray(final Collection<?> c) {
88	jsr166	1.1	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	jsr166	1.6	void testEmptyCollection(final Collection<?> c) {
109	jsr166	1.1	testEmptyIterator(c.iterator());
110	jsr166	1.6
111			check(c.iterator() == emptyIterator());
112			if (c instanceof List)
113			check(((List<?>)c).listIterator() == emptyListIterator());
114
115	jsr166	1.1	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			}