util/Collections/EmptyIterator.java

/*
 * Copyright (c) 2007, 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
 * @summary Test empty iterators, enumerations, and collections
 */

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

public class EmptyIterator {

    void test(String[] args) throws Throwable {
        testEmptyCollection(Collections.<Object>emptyList());
        testEmptyCollection(Collections.<Object>emptySet());
//         Removed jdk7 dependency from SynchronousQueue.
//         testEmptyCollection(new java.util.concurrent.
//                             SynchronousQueue<Object>());

        testEmptyMap(Collections.<Object, Object>emptyMap());

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

        testEmptyEnumeration(javax.swing.tree.DefaultMutableTreeNode
                             .EMPTY_ENUMERATION);
        testEmptyEnumeration(javax.swing.text.SimpleAttributeSet
                             .EMPTY.getAttributeNames());

        @SuppressWarnings("unchecked")
        Iterator<?> x = new sun.tools.java.MethodSet()
            .lookupName(sun.tools.java.Identifier.lookup(""));
        testEmptyIterator(x);
    }

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

    <T> void testEmptyIterator(final Iterator<T> 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<Object, Object> m) {
        check(m == emptyMap());
        check(m.entrySet().iterator() ==
              Collections.<Map.Entry<Object,Object>>emptyIterator());
        check(m.values().iterator() == emptyIterator());
        check(m.keySet().iterator() == emptyIterator());
        equal(m, unmodifiableMap(m));

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

    <E> void testToArray(final Collection<E> 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] == "");
        }
    }

    <E> void testEmptyCollection(final Collection<E> 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:	1.4
Committed:	Tue Dec 6 04:37:55 2011 UTC (12 years, 5 months ago) by jsr166
Branch:	MAIN
Changes since 1.3:	+2 -2 lines
Log Message:	@SuppressWarnings on its own line of code
#	User	Rev	Content
1	jsr166	1.1	/*
2	jsr166	1.2	* Copyright (c) 2007, 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			* @bug 5017904 6356890
27			* @summary Test empty iterators, enumerations, and collections
28			*/
29
30			import java.util.*;
31			import static java.util.Collections.*;
32
33			public class EmptyIterator {
34
35			void test(String[] args) throws Throwable {
36			testEmptyCollection(Collections.<Object>emptyList());
37			testEmptyCollection(Collections.<Object>emptySet());
38	jsr166	1.3	// Removed jdk7 dependency from SynchronousQueue.
39			// testEmptyCollection(new java.util.concurrent.
40			// SynchronousQueue<Object>());
41	jsr166	1.1
42			testEmptyMap(Collections.<Object, Object>emptyMap());
43
44			Hashtable<Object, Object> emptyTable = new Hashtable<Object, Object>();
45			testEmptyEnumeration(emptyTable.keys());
46			testEmptyEnumeration(emptyTable.elements());
47			testEmptyIterator(emptyTable.keySet().iterator());
48			testEmptyIterator(emptyTable.values().iterator());
49			testEmptyIterator(emptyTable.entrySet().iterator());
50
51			testEmptyEnumeration(javax.swing.tree.DefaultMutableTreeNode
52			.EMPTY_ENUMERATION);
53			testEmptyEnumeration(javax.swing.text.SimpleAttributeSet
54			.EMPTY.getAttributeNames());
55
56	jsr166	1.4	@SuppressWarnings("unchecked")
57			Iterator<?> x = new sun.tools.java.MethodSet()
58	jsr166	1.1	.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			}