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Applying max/min for Comparables as supplied by David Karlsen in LANG-291 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@475113 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Henri Yandell 2006-11-15 04:14:42 +00:00
parent 11a4975580
commit 012998b3d4
2 changed files with 86 additions and 1 deletions
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48
src/java/org/apache/commons/lang/ObjectUtils.java
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@ -31,6 +31,7 @@ import java.io.Serializable;
* @author Stephen Colebourne
* @author Gary Gregory
* @author Mario Winterer
* @author <a href="mailto:david@davidkarlsen.com">David J. M. Karlsen</a>
* @since 1.0
* @version $Id$
*/
@ -277,4 +278,51 @@ public class ObjectUtils {
}
}
/**
* Null safe comparison of Comparables.
*
* @param c1
* @param c2
* @return
* <ul>
* <li>If both objects are non-null and unequal, the lesser object.
* <li>If both objects are non-null and equal, c1.
* <li>If one of the comparables is null, the non-null object.
* <li>If both the comparables are null, null is returned.
* </ul>
*/
public static Object min( Comparable c1, Comparable c2 ) {
if ( c1 != null && c2 != null ) {
return c1.compareTo( c2 ) < 1 ? c1 : c2;
}
else {
return c1 != null ? c1 : c2;
}
}
/**
* Null safe comparison of Comparables.
*
* @param c1
* @param c2
* @return
* <ul>
* <li>If both objects are non-null and unequal, the greater object.
* <li>If both objects are non-null and equal, c1.
* <li>If one of the comparables is null, the non-null object.
* <li>If both the comparables are null, null is returned.
* </ul>
*/
public static Object max( Comparable c1, Comparable c2 ) {
if ( c1 != null && c2 != null ) {
return c1.compareTo( c2 ) >= 0 ? c1 : c2;
}
else {
return c1 != null ? c1 : c2;
}
}
}

39
src/test/org/apache/commons/lang/ObjectUtilsTest.java
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@ -18,6 +18,8 @@ package org.apache.commons.lang;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.Calendar;
import java.util.Date;
import junit.framework.Test;
import junit.framework.TestCase;
@ -175,5 +177,40 @@ public class ObjectUtilsTest extends TestCase {
assertTrue(ObjectUtils.NULL instanceof ObjectUtils.Null);
assertSame(ObjectUtils.NULL, SerializationUtils.clone(ObjectUtils.NULL));
}
public void testMax() {
Calendar calendar = Calendar.getInstance();
Comparable nonNullComparable1 = calendar.getTime();
Comparable nonNullComparable2 = calendar.getTime();
calendar.set( Calendar.YEAR, calendar.get( Calendar.YEAR ) -1 );
Comparable minComparable = calendar.getTime();
assertNotSame( nonNullComparable1, nonNullComparable2 );
assertSame( nonNullComparable1, ObjectUtils.max( null, nonNullComparable1 ) );
assertSame( nonNullComparable1, ObjectUtils.max( nonNullComparable1, null ) );
assertSame( nonNullComparable1, ObjectUtils.max( nonNullComparable1, nonNullComparable2 ) );
assertSame( nonNullComparable1, ObjectUtils.max( nonNullComparable1, minComparable ) );
assertSame( nonNullComparable1, ObjectUtils.max( minComparable, nonNullComparable1 ) );
}
public void testMin() {
Calendar calendar = Calendar.getInstance();
Comparable nonNullComparable1 = calendar.getTime();
Comparable nonNullComparable2 = calendar.getTime();
calendar.set( Calendar.YEAR, calendar.get( Calendar.YEAR ) -1 );
Comparable minComparable = calendar.getTime();
assertNotSame( nonNullComparable1, nonNullComparable2 );
assertSame( nonNullComparable1, ObjectUtils.min( null, nonNullComparable1 ) );
assertSame( nonNullComparable1, ObjectUtils.min( nonNullComparable1, null ) );
assertSame( nonNullComparable1, ObjectUtils.min( nonNullComparable1, nonNullComparable2 ) );
assertSame( minComparable, ObjectUtils.min( nonNullComparable1, minComparable ) );
assertSame( minComparable, ObjectUtils.min( minComparable, nonNullComparable1 ) );
}
}