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/*
* 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);}}
}
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