JAVA集合操作的利器:CollectionUtils

【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}