java CollectionUtils 包

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}