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Merge branch 'pr-89' 

This closes #89
This commit is contained in:
Bruno P. Kinoshita 2020-08-20 20:38:59 +12:00
parent 62febb3ffb 28bd7432bb
commit d5de68c2d1
3 changed files with 78 additions and 1 deletions
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3
src/changes/changes.xml
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@ -21,6 +21,9 @@
</properties>
<body>
<release version="4.5" date="2020-MM-DD" description="Maintenance release.">
<action issue="COLLECTIONS-708" dev="kinow" type="fix" due-to="dota17">
Add hashCode method to CollectionUtils that supports an equator parameter.
</action>
<action issue="COLLECTIONS-759" dev="kinow" type="fix">
Fix checkstyle issues regarding missing newline at end of file, and CRLF vs LF.
</action>

27
src/main/java/org/apache/commons/collections4/CollectionUtils.java
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@ -643,6 +643,33 @@ public class CollectionUtils {
return isEqualCollection(collect(a, transformer), collect(b, transformer));
}
/**
* Returns the hash code of the input collection using the hash method of an equator.
*
* <p>
* Returns 0 if the input collection is {@code null}.
* </p>
*
* @param <E> the element type
* @param collection the input collection
* @param equator the equator used for generate hashCode
* @return the hash code of the input collection using the hash method of an equator
* @throws NullPointerException if the equator is {@code null}
* @since 4.5
*/
public static <E> int hashCode(final Collection<? extends E> collection,
final Equator<? super E> equator) {
Objects.requireNonNull(equator, "equator");
if (null == collection) {
return 0;
}
int hashCode = 1;
for (final E e : collection) {
hashCode = 31 * hashCode + equator.hash(e);
}
return hashCode;
}
/**
* Wraps another object and uses the provided Equator to implement
* {@link #equals(Object)} and {@link #hashCode()}.

49
src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
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@ -37,6 +37,7 @@ import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Queue;
import java.util.Set;
import java.util.SortedMap;
@ -741,6 +742,52 @@ public class CollectionUtilsTest extends MockTestCase {
CollectionUtils.isEqualCollection(collectionA, collectionA, null);
}
@Test
public void testHashCode() {
final Equator<Integer> e = new Equator<Integer>() {
@Override
public boolean equate(final Integer o1, final Integer o2) {
if (o1 % 2 == 0 ^ o2 % 2 == 0) {
return false;
}
return true;
}
@Override
public int hash(final Integer o) {
return o == null ? 0 : Objects.hashCode(o);
}
};
assertEquals(collectionA.hashCode(), CollectionUtils.hashCode(collectionA, e));
}
@Test
public void testHashCodeNullCollection() {
final Equator<Integer> e = new Equator<Integer>() {
@Override
public boolean equate(final Integer o1, final Integer o2) {
if (o1 % 2 == 0 ^ o2 % 2 == 0) {
return false;
}
return true;
}
@Override
public int hash(final Integer o) {
return o == null ? 0 : Objects.hashCode(o);
}
};
final Collection<Integer> collection = null;
assertEquals(0, CollectionUtils.hashCode(collection, e));
}
@Test(expected=NullPointerException.class)
public void testHashCodeNullEquator() {
CollectionUtils.hashCode(collectionB, null);
}
@Test(expected = NullPointerException.class)
public void testIsEqualCollectionNullColl1() {
final Collection<Integer> list = new ArrayList<>(1);
@ -1073,7 +1120,7 @@ public class CollectionUtilsTest extends MockTestCase {
CollectionUtils.get(array, 2);
}
@Test(expected=IllegalArgumentException.class)
@Test(expected = IllegalArgumentException.class)
public void getFromObject() throws Exception {
// Invalid object
final Object obj = new Object();