8155600: Performance optimization of Arrays.asList().iterator()

Reviewed-by: redestad, shade, plevart, attila
This commit is contained in:
Tagir F. Valeev 2016-04-29 16:52:05 +03:00
parent a6f2cdbb0f
commit 6db653621d
2 changed files with 123 additions and 1 deletions
jdk
src/java.base/share/classes/java/util
test/java/util/Arrays

@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2016, 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
@ -4403,6 +4403,35 @@ public class Arrays {
public void sort(Comparator<? super E> c) {
Arrays.sort(a, c);
}
@Override
public Iterator<E> iterator() {
return new ArrayItr<>(a);
}
}
private static class ArrayItr<E> implements Iterator<E> {
private int cursor;
private final E[] a;
ArrayItr(E[] a) {
this.a = a;
}
@Override
public boolean hasNext() {
return cursor < a.length;
}
@Override
public E next() {
int i = cursor;
if (i >= a.length) {
throw new NoSuchElementException();
}
cursor = i + 1;
return a[i];
}
}
/**

@ -0,0 +1,93 @@
/*
* Copyright (c) 2016, 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 8155600
* @summary Tests for Arrays.asList()
* @run testng AsList
*/
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.stream.IntStream;
import org.testng.annotations.Test;
import org.testng.annotations.DataProvider;
import static org.testng.Assert.assertSame;
import static org.testng.Assert.assertTrue;
import static org.testng.Assert.assertFalse;
import static org.testng.Assert.fail;
public class AsList {
/*
* Iterator contract test
*/
@Test(dataProvider = "Arrays")
public void testIterator(Object[] array) {
Iterator<Object> itr = Arrays.asList(array).iterator();
for (int i = 0; i < array.length; i++) {
assertTrue(itr.hasNext());
assertTrue(itr.hasNext()); // must be idempotent
assertSame(array[i], itr.next());
try {
itr.remove();
fail("Remove must throw");
} catch (UnsupportedOperationException ex) {
// expected
}
}
assertFalse(itr.hasNext());
for (int i = 0; i < 3; i++) {
assertFalse(itr.hasNext());
try {
itr.next();
fail("Next succeed when there's no data left");
} catch (NoSuchElementException ex) {
// expected
}
}
}
@DataProvider(name = "Arrays")
public static Object[][] arrays() {
Object[][] arrays = {
{ new Object[] { } },
{ new Object[] { 1 } },
{ new Object[] { null } },
{ new Object[] { null, 1 } },
{ new Object[] { 1, null } },
{ new Object[] { null, null } },
{ new Object[] { null, 1, 2 } },
{ new Object[] { 1, null, 2 } },
{ new Object[] { 1, 2, null } },
{ new Object[] { null, null, null } },
{ new Object[] { 1, 2, 3, null, 4 } },
{ new Object[] { "a", "a", "a", "a" } },
{ IntStream.range(0, 100).boxed().toArray() }
};
return arrays;
}
}