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[COLLECTIONS-540] Added CollectionUtils#get(Enumeration, int), simplified code of CollectionUtils#get(Object, int). Thanks to Daniel Stewart, Issam El Atif. This closes #6.

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git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1647955 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart 2014-12-26 11:06:23 +00:00
parent f0b18d27f0
commit 45a0337e1d
3 changed files with 55 additions and 19 deletions
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4
src/changes/changes.xml
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@ -22,6 +22,10 @@
<body>
<release version="4.1" date="TBD" description="">
<action issue="COLLECTIONS-540" dev="tn" type="fix" due-to="Daniel Stewart, Issam El Atif">
Added overloaded method "CollectionUtils#get(Enumeration, int)" and simplified
code for "CollectionUtils#get(Object, int)".
</action>
<action issue="COLLECTIONS-518" dev="tn" type="fix" due-to="Dipanjan Laha">
The abstract decorator "AbstractIterableGetMapDecorator" was not declared
abstract.

48
src/main/java/org/apache/commons/collections4/CollectionUtils.java
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@ -1198,6 +1198,35 @@ public class CollectionUtils {
throw new IndexOutOfBoundsException("Entry does not exist: " + i);
}
/**
* Returns the <code>index</code>-th value in the {@link Enumeration}, throwing
* <code>IndexOutOfBoundsException</code> if there is no such element.
* <p>
* The Enumeration is advanced to <code>index</code> (or to the end, if
* <code>index</code> exceeds the number of entries) as a side effect of this method.
*
* @param e the enumeration to get a value from
* @param index the index to get
* @param <T> the type of object in the {@link Enumeration}
* @return the object at the specified index
* @throws IndexOutOfBoundsException if the index is invalid
* @throws IllegalArgumentException if the object type is invalid
* @since 4.1
*/
public static <T> T get(final Enumeration<T> e, final int index) {
int i = index;
checkIndexBounds(i);
while (e.hasMoreElements()) {
i--;
if (i == -1) {
return e.nextElement();
} else {
e.nextElement();
}
}
throw new IndexOutOfBoundsException("Entry does not exist: " + i);
}
/**
* Ensures an index is not negative.
* @param index the index to check.
@ -1272,28 +1301,13 @@ public class CollectionUtils {
return ((Object[]) object)[i];
} else if (object instanceof Iterator<?>) {
final Iterator<?> it = (Iterator<?>) object;
while (it.hasNext()) {
i--;
if (i == -1) {
return it.next();
}
it.next();
}
throw new IndexOutOfBoundsException("Entry does not exist: " + i);
return get(it, i);
} else if (object instanceof Collection<?>) {
final Iterator<?> iterator = ((Collection<?>) object).iterator();
return get(iterator, i);
} else if (object instanceof Enumeration<?>) {
final Enumeration<?> it = (Enumeration<?>) object;
while (it.hasMoreElements()) {
i--;
if (i == -1) {
return it.nextElement();
} else {
it.nextElement();
}
}
throw new IndexOutOfBoundsException("Entry does not exist: " + i);
return get(it, i);
} else if (object == null) {
throw new IllegalArgumentException("Unsupported object type: null");
} else {

22
src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
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@ -1600,8 +1600,26 @@ public class CollectionUtilsTest extends MockTestCase {
assertEquals(2, CollectionUtils.get((Object)collectionA, 2));
assertEquals(2, CollectionUtils.get((Object)collectionA.iterator(), 2));
final Map<Integer, Integer> map = CollectionUtils.getCardinalityMap(collectionA);
assertEquals(map.entrySet().iterator().next(), CollectionUtils.get(
(Object)map, 0));
assertEquals(map.entrySet().iterator().next(), CollectionUtils.get((Object)map, 0));
}
@Test
public void getIterator() {
final Iterator<Integer> it = collectionA.iterator();
assertEquals(Integer.valueOf(2), CollectionUtils.get(it, 2));
assertTrue(it.hasNext());
assertEquals(Integer.valueOf(4), CollectionUtils.get(it, 6));
assertFalse(it.hasNext());
}
@Test
public void getEnumeration() {
final Vector<Integer> vectorA = new Vector<Integer>(collectionA);
final Enumeration<Integer> e = vectorA.elements();
assertEquals(Integer.valueOf(2), CollectionUtils.get(e, 2));
assertTrue(e.hasMoreElements());
assertEquals(Integer.valueOf(4), CollectionUtils.get(e, 6));
assertFalse(e.hasMoreElements());
}
@Test