org.apache.commons.collections4.CollectionUtils

 

 

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{// 集合判空     List<Integer> list = new ArrayList<>();     list.add(2);     list.add(1);     list.add(3);       if (CollectionUtils.isEmpty(list)) {         System.out.println("集合为空");     }       if (CollectionUtils.isNotEmpty(list)) {         System.out.println("集合不为空");     } }   {// 对两个集合进行操作     List<Integer> list = new ArrayList<>();     list.add(2);     list.add(1);     list.add(3);       List<Integer> list2 = new ArrayList<>();     list2.add(2);     list2.add(4);       //获取并集     Collection<Integer> unionList = CollectionUtils.union(list, list2);     System.out.println(unionList);       //获取交集     Collection<Integer> intersectionList = CollectionUtils.intersection(list, list2);     System.out.println(intersectionList);       //获取交集的补集     Collection<Integer> disjunctionList = CollectionUtils.disjunction(list, list2);     System.out.println(disjunctionList);       //获取差集     Collection<Integer> subtractList = CollectionUtils.subtract(list, list2);     System.out.println(subtractList); }