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Polishing

This commit is contained in:
Juergen Hoeller 2014-06-04 21:49:23 +02:00
parent f7b465390c
commit 2cf88ac6a3
2 changed files with 76 additions and 43 deletions
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46
spring-core/src/main/java/org/springframework/util/CompositeIterator.java
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@ -1,5 +1,5 @@
/*
* Copyright 2002-2012 the original author or authors.
* Copyright 2002-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@ -13,46 +13,48 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.util;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.LinkedHashSet;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* Iterator that combines multiple other iterators.
* This implementation maintains a list of iterators which are invoked in sequence until all iterators are exhausted.
* Composite iterator that combines multiple other iterators,
* as registered via {@link #add(Iterator)}.
*
* <p>This implementation maintains a linked set of iterators
* which are invoked in sequence until all iterators are exhausted.
*
* @author Erwin Vervaet
* @author Juergen Hoeller
* @since 3.0
*/
public class CompositeIterator<E> implements Iterator<E> {
private List<Iterator<E>> iterators = new LinkedList<Iterator<E>>();
private final Set<Iterator<E>> iterators = new LinkedHashSet<Iterator<E>>();
private boolean inUse = false;
/**
* Create a new composite iterator. Add iterators using the {@link #add(Iterator)} method.
*/
public CompositeIterator() {
}
/**
* Add given iterator to this composite.
*/
public void add(Iterator<E> iterator) {
Assert.state(!inUse, "You can no longer add iterator to a composite iterator that's already in use");
if (iterators.contains(iterator)) {
Assert.state(!this.inUse, "You can no longer add iterators to a composite iterator that's already in use");
if (this.iterators.contains(iterator)) {
throw new IllegalArgumentException("You cannot add the same iterator twice");
}
iterators.add(iterator);
this.iterators.add(iterator);
}
@Override
public boolean hasNext() {
inUse = true;
for (Iterator<Iterator<E>> it = iterators.iterator(); it.hasNext();) {
if (it.next().hasNext()) {
this.inUse = true;
for (Iterator<E> iterator : this.iterators) {
if (iterator.hasNext()) {
return true;
}
}
@ -61,18 +63,18 @@ public class CompositeIterator<E> implements Iterator<E> {
@Override
public E next() {
inUse = true;
for (Iterator<Iterator<E>> it = iterators.iterator(); it.hasNext();) {
Iterator<E> iterator = it.next();
this.inUse = true;
for (Iterator<E> iterator : this.iterators) {
if (iterator.hasNext()) {
return iterator.next();
}
}
throw new NoSuchElementException("Exhausted all iterators");
throw new NoSuchElementException("All iterators exhausted");
}
@Override
public void remove() {
throw new UnsupportedOperationException("Remove is not supported");
throw new UnsupportedOperationException("CompositeIterator does not support remove()");
}
}

73
spring-core/src/test/java/org/springframework/util/CompositeIteratorTests.java
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@ -1,3 +1,19 @@
/*
* Copyright 2002-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.util;
import java.util.Arrays;
@ -5,29 +21,36 @@ import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import junit.framework.TestCase;
import org.junit.Test;
import static org.junit.Assert.*;
/**
* Test case for {@link CompositeIterator}.
*
* @author Erwin Vervaet
* @author Juergen Hoeller
*/
public class CompositeIteratorTests extends TestCase {
public class CompositeIteratorTests {
@Test
public void testNoIterators() {
CompositeIterator it = new CompositeIterator();
CompositeIterator<String> it = new CompositeIterator<String>();
assertFalse(it.hasNext());
try {
it.next();
fail();
} catch (NoSuchElementException e) {
}
catch (NoSuchElementException ex) {
// expected
}
}
@Test
public void testSingleIterator() {
CompositeIterator it = new CompositeIterator();
it.add(Arrays.asList(new String[] { "0", "1" }).iterator());
CompositeIterator<String> it = new CompositeIterator<String>();
it.add(Arrays.asList("0", "1").iterator());
for (int i = 0; i < 2; i++) {
assertTrue(it.hasNext());
assertEquals(String.valueOf(i), it.next());
@ -36,16 +59,18 @@ public class CompositeIteratorTests extends TestCase {
try {
it.next();
fail();
} catch (NoSuchElementException e) {
}
catch (NoSuchElementException ex) {
// expected
}
}
@Test
public void testMultipleIterators() {
CompositeIterator it = new CompositeIterator();
it.add(Arrays.asList(new String[] { "0", "1" }).iterator());
it.add(Arrays.asList(new String[] { "2" }).iterator());
it.add(Arrays.asList(new String[] { "3", "4" }).iterator());
CompositeIterator<String> it = new CompositeIterator<String>();
it.add(Arrays.asList("0", "1").iterator());
it.add(Arrays.asList("2").iterator());
it.add(Arrays.asList("3", "4").iterator());
for (int i = 0; i < 5; i++) {
assertTrue(it.hasNext());
assertEquals(String.valueOf(i), it.next());
@ -54,43 +79,49 @@ public class CompositeIteratorTests extends TestCase {
try {
it.next();
fail();
} catch (NoSuchElementException e) {
}
catch (NoSuchElementException ex) {
// expected
}
}
@Test
public void testInUse() {
List list = Arrays.asList(new String[] { "0", "1" });
CompositeIterator it = new CompositeIterator();
List<String> list = Arrays.asList("0", "1");
CompositeIterator<String> it = new CompositeIterator<String>();
it.add(list.iterator());
it.hasNext();
try {
it.add(list.iterator());
fail();
} catch (IllegalStateException e) {
}
catch (IllegalStateException ex) {
// expected
}
it = new CompositeIterator();
it = new CompositeIterator<String>();
it.add(list.iterator());
it.next();
try {
it.add(list.iterator());
fail();
} catch (IllegalStateException e) {
}
catch (IllegalStateException ex) {
// expected
}
}
@Test
public void testDuplicateIterators() {
List list = Arrays.asList(new String[] { "0", "1" });
Iterator iterator = list.iterator();
CompositeIterator it = new CompositeIterator();
List<String> list = Arrays.asList("0", "1");
Iterator<String> iterator = list.iterator();
CompositeIterator<String> it = new CompositeIterator<String>();
it.add(iterator);
it.add(list.iterator());
try {
it.add(iterator);
fail();
} catch (IllegalArgumentException e) {
}
catch (IllegalArgumentException ex) {
// expected
}
}