From b135568b5d7c98e3798e34d97cea74bb686eedb5 Mon Sep 17 00:00:00 2001
From: kaloyane <kaloyane>
Date: Tue, 22 Nov 2011 17:15:08 +0000
Subject: [PATCH] introduce a helper sort method which allows sorting of
non-comparable objects
SVN: 23768
---
.../common/collections/CollectionUtils.java | 20 ++++++++++++++++++
.../collections/CollectionUtilsTest.java | 21 +++++++++++++++++++
2 files changed, 41 insertions(+)
diff --git a/common/source/java/ch/systemsx/cisd/common/collections/CollectionUtils.java b/common/source/java/ch/systemsx/cisd/common/collections/CollectionUtils.java
index 9380b254941..3a73b50409b 100644
--- a/common/source/java/ch/systemsx/cisd/common/collections/CollectionUtils.java
+++ b/common/source/java/ch/systemsx/cisd/common/collections/CollectionUtils.java
@@ -20,6 +20,7 @@ import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
+import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
@@ -343,4 +344,23 @@ public final class CollectionUtils
{
return (list != null) ? list : Collections.<E> emptyList();
}
+
+ /**
+ * Sorts a collection of objects with a key extractor providing sort criteria.
+ * <p>
+ * The method is useful when we would like to sort a list of non-Comparable objects.
+ */
+ public static <E, C extends Comparable<C>> void sort(List<E> list,
+ final IKeyExtractor<C, E> sortCriteriaKeyExtractor)
+ {
+ Collections.sort(list, new Comparator<E>()
+ {
+ public int compare(E o1, E o2)
+ {
+ C key1 = sortCriteriaKeyExtractor.getKey(o1);
+ C key2 = sortCriteriaKeyExtractor.getKey(o2);
+ return key1.compareTo(key2);
+ }
+ });
+ }
}
\ No newline at end of file
diff --git a/common/sourceTest/java/ch/systemsx/cisd/common/collections/CollectionUtilsTest.java b/common/sourceTest/java/ch/systemsx/cisd/common/collections/CollectionUtilsTest.java
index e17fc31255a..3c16dda1aea 100644
--- a/common/sourceTest/java/ch/systemsx/cisd/common/collections/CollectionUtilsTest.java
+++ b/common/sourceTest/java/ch/systemsx/cisd/common/collections/CollectionUtilsTest.java
@@ -19,7 +19,9 @@ package ch.systemsx.cisd.common.collections;
import static org.testng.AssertJUnit.assertEquals;
import static org.testng.AssertJUnit.assertTrue;
+import java.util.Arrays;
import java.util.Collection;
+import java.util.List;
import org.apache.commons.lang.StringUtils;
import org.testng.annotations.Test;
@@ -116,4 +118,23 @@ public final class CollectionUtilsTest
}
assertTrue("IToStringConverter can not be null.", exceptionThrown);
}
+
+ @Test
+ public void testSort()
+ {
+ IKeyExtractor<Integer, String> lengthExtractor = new IKeyExtractor<Integer, String>()
+ {
+
+ public Integer getKey(String e)
+ {
+ return e.length();
+ }
+ };
+
+ List<String> strings = Arrays.asList("bbbb", "z", "ccc", "aa");
+ List<String> sortedByLength = Arrays.asList("z", "aa", "ccc", "bbbb");
+
+ CollectionUtils.sort(strings, lengthExtractor);
+ assertEquals(sortedByLength, strings);
+ }
}
--
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