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 java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.concurrent.SynchronousQueue;

import static java.util.Collections.emptyEnumeration;
import static java.util.Collections.emptyIterator;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptyListIterator;
import static java.util.Collections.emptyMap;
import static java.util.Collections.emptySet;
import static java.util.Collections.nCopies;
import static java.util.Collections.unmodifiableMap;

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:	1.7
Committed:	Mon Jan 8 03:12:03 2018 UTC (6 years, 4 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.6:	+17 -2 lines
Log Message:	organize imports
#	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	1.7	import java.util.Collection;
31			import java.util.Collections;
32			import java.util.Enumeration;
33			import java.util.Hashtable;
34			import java.util.Iterator;
35			import java.util.List;
36			import java.util.Map;
37			import java.util.NoSuchElementException;
38	jsr166	1.6	import java.util.concurrent.SynchronousQueue;
39	jsr166	1.1
40	jsr166	1.7	import static java.util.Collections.emptyEnumeration;
41			import static java.util.Collections.emptyIterator;
42			import static java.util.Collections.emptyList;
43			import static java.util.Collections.emptyListIterator;
44			import static java.util.Collections.emptyMap;
45			import static java.util.Collections.emptySet;
46			import static java.util.Collections.nCopies;
47			import static java.util.Collections.unmodifiableMap;
48
49	jsr166	1.1	public class EmptyIterator {
50
51			void test(String[] args) throws Throwable {
52	jsr166	1.6	testEmptyCollection(emptyList());
53			testEmptyCollection(emptySet());
54			testEmptyCollection(new SynchronousQueue<Object>());
55			testEmptyMap(emptyMap());
56	jsr166	1.1
57	jsr166	1.6	Hashtable<?,?> emptyTable = new Hashtable<>();
58	jsr166	1.1	testEmptyEnumeration(emptyTable.keys());
59			testEmptyEnumeration(emptyTable.elements());
60			testEmptyIterator(emptyTable.keySet().iterator());
61			testEmptyIterator(emptyTable.values().iterator());
62			testEmptyIterator(emptyTable.entrySet().iterator());
63
64	jsr166	1.6	final Enumeration<EmptyIterator> finalEmptyTyped = emptyEnumeration();
65			testEmptyEnumeration(finalEmptyTyped);
66
67			final Enumeration<?> finalEmptyAbstract = emptyEnumeration();
68			testEmptyEnumeration(finalEmptyAbstract);
69
70			testEmptyIterator(emptyIterator());
71	jsr166	1.1	}
72
73	jsr166	1.6	void testEmptyEnumeration(final Enumeration<?> e) {
74			check(e == emptyEnumeration());
75			check(!e.hasMoreElements());
76	jsr166	1.1	THROWS(NoSuchElementException.class,
77			new F(){void f(){ e.nextElement(); }});
78			}
79
80	jsr166	1.6	void testEmptyIterator(final Iterator<?> it) {
81			check(it == emptyIterator());
82	jsr166	1.1	check(! it.hasNext());
83			THROWS(NoSuchElementException.class,
84			new F(){void f(){ it.next(); }});
85			THROWS(IllegalStateException.class,
86			new F(){void f(){ it.remove(); }});
87			}
88
89	jsr166	1.6	void testEmptyMap(Map<?,?> m) {
90			check(m == emptyMap());
91	jsr166	1.1	check(m.entrySet().iterator() ==
92	jsr166	1.6	Collections.<Map.Entry<?,?>>emptyIterator());
93	jsr166	1.1	check(m.values().iterator() == emptyIterator());
94			check(m.keySet().iterator() == emptyIterator());
95			equal(m, unmodifiableMap(m));
96
97			testEmptyCollection(m.keySet());
98			testEmptyCollection(m.entrySet());
99			testEmptyCollection(m.values());
100			}
101
102	jsr166	1.6	void testToArray(final Collection<?> c) {
103	jsr166	1.1	Object[] a = c.toArray();
104			equal(a.length, 0);
105			equal(a.getClass().getComponentType(), Object.class);
106			THROWS(NullPointerException.class,
107			new F(){void f(){ c.toArray((Object[])null); }});
108
109			{
110			String[] t = new String[0];
111			check(c.toArray(t) == t);
112			}
113
114			{
115			String[] t = nCopies(10, "").toArray(new String[0]);
116			check(c.toArray(t) == t);
117			check(t[0] == null);
118			for (int i=1; i<t.length; i++)
119			check(t[i] == "");
120			}
121			}
122
123	jsr166	1.6	void testEmptyCollection(final Collection<?> c) {
124	jsr166	1.1	testEmptyIterator(c.iterator());
125	jsr166	1.6
126			check(c.iterator() == emptyIterator());
127			if (c instanceof List)
128			check(((List<?>)c).listIterator() == emptyListIterator());
129
130	jsr166	1.1	testToArray(c);
131			}
132
133			//--------------------- Infrastructure ---------------------------
134			volatile int passed = 0, failed = 0;
135			void pass() {passed++;}
136			void fail() {failed++; Thread.dumpStack();}
137			void fail(String msg) {System.err.println(msg); fail();}
138			void unexpected(Throwable t) {failed++; t.printStackTrace();}
139			void check(boolean cond) {if (cond) pass(); else fail();}
140			void equal(Object x, Object y) {
141			if (x == null ? y == null : x.equals(y)) pass();
142			else fail(x + " not equal to " + y);}
143			public static void main(String[] args) throws Throwable {
144			new EmptyIterator().instanceMain(args);}
145			void instanceMain(String[] args) throws Throwable {
146			try {test(args);} catch (Throwable t) {unexpected(t);}
147			System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
148			if (failed > 0) throw new AssertionError("Some tests failed");}
149			abstract class F {abstract void f() throws Throwable;}
150			void THROWS(Class<? extends Throwable> k, F... fs) {
151			for (F f : fs)
152			try {f.f(); fail("Expected " + k.getName() + " not thrown");}
153			catch (Throwable t) {
154			if (k.isAssignableFrom(t.getClass())) pass();
155			else unexpected(t);}}
156			}