JAVA集合操作的利器:CollectionUtils

来源：互联网发布：java web项目开发书籍编辑：程序博客网时间：2024/05/02 02:56

【IT168 技术】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}