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<dependency><groupId>org.apache.commons</groupId><artifactId>commons-collections4</artifactId><version>4.4</version></dependency>
@Testpublic void SetOperations() {List<String> listA = new ArrayList<>();listA.add("a");listA.add("b");listA.add("c");List<String> listB = new ArrayList<>();listB.add("a");listB.add("b");listB.add("d");// 判断集合为空System.out.println("判断集合为空:" + CollectionUtils.isEmpty(listA));// 判断集合不为空System.out.println("判断集合不为空:" + CollectionUtils.isNotEmpty(listA));// 两个集合取交集Collection<String> collection = CollectionUtils.retainAll(listA, listB);// 两个集合取并集Collection<String> collection2 = CollectionUtils.union(listA, listB);for (String s : collection2) {System.out.println("两个集合取并集:" + s);}// 两个集合取差集Collection<String> collection3 = CollectionUtils.subtract(listA, listB);for (String s : collection3) {System.out.println("两个集合取差集:" + s);}}
