<dependency>

          <groupId>commons-collections</groupId>

          <artifactId>commons-collections</artifactId>

       </dependency>

package cn.xm.exam.test;

import java.util.ArrayList;

import java.util.Collection;

import java.util.List;

import org.apache.commons.collections.CollectionUtils;

public class test {

    public static void main(String[] args) {

        List<String> list = new ArrayList<String>();

        list.add("str1");

        list.add("str2");

        List<String> list1 = new ArrayList<String>();

        list1.add("str1");

        list1.add("str21");

        // 判断是否有任何一个相同的元素

        System.out.println(CollectionUtils.containsAny(list, list1));

        // 求并集(自动去重)

        List<String> list3 = (List<String>) CollectionUtils.union(list, list1);

        System.out.println(list3);

        // 求交集(两个集合中都有的元素)

        Collection intersection = CollectionUtils.intersection(list, list1);

        System.out.println("intersection->" + intersection);

        // 求差集(并集去掉交集，也就是list中有list1中没有，list1中有list中没有)

        Collection intersection1 = CollectionUtils.disjunction(list, list1);

        System.out.println("intersection1->" + intersection1);

        // 获取一个同步的集合

        Collection synchronizedCollection = CollectionUtils.synchronizedCollection(list);

        // 验证集合是否为null或者集合的大小是否为0，同理有isNouEmpty方法

        List list4 = null;

        List list5 = new ArrayList<>();

        System.out.println(CollectionUtils.isEmpty(list4));

        System.out.println(CollectionUtils.isEmpty(list5));

    }

}

        List<String> list = new ArrayList<>();

        String s[] = { "1", "2" };

        CollectionUtils.addAll(list, s);

        list.add("3");

        System.out.println(list);

package cn.xm.exam.test;

import java.util.HashMap;

import java.util.Map;

import org.apache.commons.collections.MapUtils;

import org.apache.commons.lang.NumberUtils;

import ognl.MapElementsAccessor;

public class test {

    public static void main(String[] args) {

        Map map = null;

        Map map2 = new HashMap();

        Map map3 = new HashMap<>();

        map3.put("xxx", "xxx");

        // 检验为empty可以验证null和size为0的情况

        System.out.println(MapUtils.isEmpty(map));

        System.out.println(MapUtils.isEmpty(map2));

        System.out.println(MapUtils.isEmpty(map3));

        String string = MapUtils.getString(map3, "eee");

        String string2 = MapUtils.getString(map3, "xxx");

        Integer integer = MapUtils.getInteger(map3, "xxx");

        System.out.println("string->" + string);

        System.out.println("string2->" + string2);

        System.out.println("integer->" + integer);

        System.out.println(integer == null);

    }

}

    public static boolean isEmpty(Map map) {

        return (map == null || map.isEmpty());

    }

    public boolean isEmpty() {

        return size == 0;

    }

        //获取字符串,如果获取不到可以返回一个默认值

        String string3 = MapUtils.getString(map3, "eee","没有值");

    /**

     *  Looks up the given key in the given map, converting the result into

     *  a string, using the default value if the the conversion fails.

     *

     *  @param map  the map whose value to look up

     *  @param key  the key of the value to look up in that map

     *  @param defaultValue  what to return if the value is null or if the

     *     conversion fails

     *  @return  the value in the map as a string, or defaultValue if the

     *    original value is null, the map is null or the string conversion

     *    fails

     */

    public static String getString( Map map, Object key, String defaultValue ) {

        String answer = getString( map, key );

        if ( answer == null ) {

            answer = defaultValue;

        }

        return answer;

    }