使用 CollectionUtils 中四个方法之一执行集合操作.这四种分别是 union(),intersection();disjunction(); subtract();
下列例子就是演示了如何使用上述四个方法处理两个 Collection;
注: 这些方法都是数学的集合算法
import
java.util.Arrays;
import
java.util.Collection;
import
java.util.Collections;
import
java.util.List;
import
org.apache.commons.collections.CollectionUtils;
import
org.apache.commons.lang.ArrayUtils;
public
class
CollectionUtilsIntro {
@SuppressWarnings(
"
unchecked
"
)
public
static
void
main(String[] args) {
String[] arrayA
=
new
String[] {
"
1
"
,
"
2
"
,
"
3
"
,
"
3
"
,
"
4
"
,
"
5
"
};
String[] arrayB
=
new
String[] {
"
3
"
,
"
4
"
,
"
4
"
,
"
5
"
,
"
6
"
,
"
7
"
};
List
<
String
>
a
=
Arrays.asList(arrayA);
List
<
String
>
b
=
Arrays.asList(arrayB);
//
并集
Collection
<
String
>
union
=
CollectionUtils.union(a, b);
//
交集
Collection
<
String
>
intersection
=
CollectionUtils.intersection(a, b);
//
交集的补集
Collection
<
String
>
disjunction
=
CollectionUtils.disjunction(a, b);
//
集合相减
Collection
<
String
>
subtract
=
CollectionUtils.subtract(a, b);
Collections.sort((List
<
String
>
) union);
Collections.sort((List
<
String
>
) intersection);
Collections.sort((List
<
String
>
) disjunction);
Collections.sort((List
<
String
>
) subtract);
System.out.println(
"
A:
"
+
ArrayUtils.toString(a.toArray()));
System.out.println(
"
B:
"
+
ArrayUtils.toString(b.toArray()));
System.out.println(
"
--------------------------------------------
"
);
System.out.println(
"
Union(A, B):
"
+
ArrayUtils.toString(union.toArray()));
System.out.println(
"
Intersection(A, B):
"
+
ArrayUtils.toString(intersection.toArray()));
System.out.println(
"
Disjunction(A, B):
"
+
ArrayUtils.toString(disjunction.toArray()));
System.out.println(
"
Subtract(A, B):
"
+
ArrayUtils.toString(subtract.toArray()));
}
}
输出如下:
A: {1,2,3,3,4,5}
B: {3,4,4,5,6,7}
--------------------------------------------
Union(A, B): {1,2,3,3,4,4,5,6,7}
Intersection(A, B): {3,4,5}
Disjunction(A, B): {1,2,3,4,6,7}
Subtract(A, B): {1,2,3}