Add size(Object) method to find the size of various collection-like objects
bug 27909, from Steven Melzer git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131612 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne
parent
c1d10f003e
commit
c324046a54
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@ -34,6 +34,7 @@ No interface changes, or deprecations have occurred.
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<li>AbstractHashedMap,AbstractLinkedMap - Add methods to access entry methods when protected scope blocks</li>
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<li>Functors - Add get methods to retrieve internal state [27515]</li>
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<li>MultiHashMap - Add five methods to improve the API</li>
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<li>CollectionUtils - Add size(Object) method to find the size of various collection-like objects [27909]</li>
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</ul>
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<center><h3>BUG FIXES</h3></center>
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@ -174,6 +174,9 @@
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<contributor>
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<name>Brian McCallister</name>
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</contributor>
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<contributor>
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<name>Steven Melzer</name>
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</contributor>
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<contributor>
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<name>Leon Messerschmidt</name>
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</contributor>
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@ -37,7 +37,7 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
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* Provides utility methods and decorators for {@link Collection} instances.
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*
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* @since Commons Collections 1.0
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* @version $Revision: 1.56 $ $Date: 2004/02/18 01:15:42 $
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* @version $Revision: 1.57 $ $Date: 2004/03/31 21:43:27 $
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*
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* @author Rodney Waldhoff
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* @author Paul Jack
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@ -48,6 +48,7 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
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* @author Matthew Hawthorne
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* @author Janek Bogucki
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* @author Phil Steitz
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* @author Steven Melzer
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*/
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public class CollectionUtils {
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@ -739,13 +740,13 @@ public class CollectionUtils {
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return ((Object[])obj)[idx];
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}
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else if(obj instanceof Enumeration) {
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Enumeration enum = (Enumeration)obj;
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while(enum.hasMoreElements()) {
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Enumeration it = (Enumeration)obj;
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while(it.hasMoreElements()) {
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idx--;
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if(idx == -1) {
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return enum.nextElement();
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return it.nextElement();
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} else {
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enum.nextElement();
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it.nextElement();
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}
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}
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}
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@ -803,52 +804,88 @@ public class CollectionUtils {
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*/
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public static Object get(Object object, int index) {
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if (index < 0) {
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throw new IndexOutOfBoundsException("Index cannot be negative.");
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throw new IndexOutOfBoundsException("Index cannot be negative: " + index);
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}
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if(object instanceof Map) {
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Map map = (Map)object;
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if (object instanceof Map) {
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Map map = (Map) object;
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Iterator iterator = map.entrySet().iterator();
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return get(iterator, index);
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}
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else if(object instanceof List) {
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return ((List)object).get(index);
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}
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else if(object instanceof Object[]) {
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return ((Object[])object)[index];
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}
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else if(object instanceof Enumeration) {
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Enumeration enum = (Enumeration)object;
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while(enum.hasMoreElements()) {
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} else if (object instanceof List) {
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return ((List) object).get(index);
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} else if (object instanceof Object[]) {
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return ((Object[]) object)[index];
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} else if (object instanceof Enumeration) {
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Enumeration it = (Enumeration) object;
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while (it.hasMoreElements()) {
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index--;
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if(index == -1) {
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return enum.nextElement();
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if (index == -1) {
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return it.nextElement();
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} else {
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enum.nextElement();
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it.nextElement();
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}
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}
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throw new IndexOutOfBoundsException("Entry does not exist.");
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}
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else if(object instanceof Iterator) {
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return get((Iterator)object, index);
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}
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else if(object instanceof Collection) {
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Iterator iterator = ((Collection)object).iterator();
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throw new IndexOutOfBoundsException("Entry does not exist: " + index);
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} else if (object instanceof Iterator) {
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Iterator it = (Iterator) object;
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while (it.hasNext()) {
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index--;
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if (index == -1) {
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return it.next();
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} else {
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it.next();
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}
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}
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throw new IndexOutOfBoundsException("Entry does not exist: " + index);
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} else if (object instanceof Collection) {
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Iterator iterator = ((Collection) object).iterator();
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return get(iterator, index);
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} else {
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throw new IllegalArgumentException("Unsupported object type.");
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throw new IllegalArgumentException("Unsupported object type: " +
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(object == null ? "null" : object.getClass().getName()));
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}
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}
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private static Object get(Iterator iterator, int index) {
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while(iterator.hasNext()) {
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index--;
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if(index == -1) {
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return iterator.next();
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} else {
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iterator.next();
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/**
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* Gets the size of the collection/iterator specified.
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* <p>
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* This method can handles objects as follows
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* <ul>
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* <li>Collection - the collection size
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* <li>Map - the map size
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* <li>Object array - the array size
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* <li>Iterator - the number of elements remaining in the iterator
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* <li>Enumeration - the number of elements remaining in the enumeration
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* </ul>
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*
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* @param object the object to get the size of
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* @return the size of the specified collection
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* @throws IllegalArgumentException thrown if object is not recognised or null
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*/
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public static int size(Object object) {
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int total = 0;
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if (object instanceof Map) {
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total = ((Map) object).size();
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} else if (object instanceof Collection) {
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total = ((Collection) object).size();
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} else if (object instanceof Object[]) {
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total = ((Object[]) object).length;
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} else if (object instanceof Iterator) {
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Iterator it = (Iterator) object;
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while (it.hasNext()) {
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total++;
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it.next();
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}
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} else if (object instanceof Enumeration) {
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Enumeration it = (Enumeration) object;
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while (it.hasMoreElements()) {
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total++;
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it.nextElement();
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}
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} else {
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throw new IllegalArgumentException("Unsupported object type: " +
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(object == null ? "null" : object.getClass().getName()));
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}
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throw new IndexOutOfBoundsException("Entry does not exist.");
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return total;
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}
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/**
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@ -46,8 +46,9 @@ import org.apache.commons.collections.collection.UnmodifiableCollection;
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* @author Matthew Hawthorne
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* @author Stephen Colebourne
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* @author Phil Steitz
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* @author Steven Melzer
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*
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* @version $Revision: 1.35 $ $Date: 2004/02/18 01:20:35 $
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* @version $Revision: 1.36 $ $Date: 2004/03/31 21:43:27 $
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*/
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public class TestCollectionUtils extends TestCase {
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@ -686,7 +687,65 @@ public class TestCollectionUtils extends TestCase {
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}
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}
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public void testSize_List() {
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List list = new ArrayList();
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assertEquals(0, CollectionUtils.size(list));
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list.add("a");
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assertEquals(1, CollectionUtils.size(list));
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list.add("b");
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assertEquals(2, CollectionUtils.size(list));
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}
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public void testSize_Map() {
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Map map = new HashMap();
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assertEquals(0, CollectionUtils.size(map));
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map.put("1", "a");
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assertEquals(1, CollectionUtils.size(map));
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map.put("2", "b");
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assertEquals(2, CollectionUtils.size(map));
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}
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public void testSize_Array() {
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Object[] objectArray = new Object[0];
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assertEquals(0, CollectionUtils.size(objectArray));
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String[] stringArray = new String[3];
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assertEquals(3, CollectionUtils.size(stringArray));
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stringArray[0] = "a";
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stringArray[1] = "b";
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stringArray[2] = "c";
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assertEquals(3, CollectionUtils.size(stringArray));
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}
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public void testSize_Enumeration() {
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Vector list = new Vector();
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assertEquals(0, CollectionUtils.size(list.elements()));
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list.add("a");
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assertEquals(1, CollectionUtils.size(list.elements()));
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list.add("b");
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assertEquals(2, CollectionUtils.size(list.elements()));
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}
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public void testSize_Iterator() {
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List list = new ArrayList();
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assertEquals(0, CollectionUtils.size(list.iterator()));
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list.add("a");
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assertEquals(1, CollectionUtils.size(list.iterator()));
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list.add("b");
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assertEquals(2, CollectionUtils.size(list.iterator()));
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}
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public void testSize_Other() {
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try {
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CollectionUtils.size(null);
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fail("Expecting IllegalArgumentException");
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} catch (IllegalArgumentException e) {}
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try {
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CollectionUtils.size("not a list");
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fail("Expecting IllegalArgumentException");
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} catch (IllegalArgumentException e) {}
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try {
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CollectionUtils.size(new int[0]);
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fail("Expecting IllegalArgumentException");
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} catch (IllegalArgumentException e) {}
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}
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//-----------------------------------------------------------------------
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private static Predicate EQUALS_TWO = new Predicate() {
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public boolean evaluate(Object input) {
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return (input.equals("Two"));
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