转:Apache common包 CollectionUtils 使用详解
集合判断:
例1: 判断集合是否为空:
CollectionUtils.isEmpty(null): true
CollectionUtils.isEmpty(new ArrayList()): true
CollectionUtils.isEmpty({a,b}): false
例2: 判断集合是否不为空:
CollectionUtils.isNotEmpty(null): false
CollectionUtils.isNotEmpty(new ArrayList()): false
CollectionUtils.isNotEmpty({a,b}): true
2个集合间的操作:
集合a: {1,2,3,3,4,5}
集合b: {3,4,4,5,6,7}
CollectionUtils.union(a, b)(并集): {1,2,3,3,4,4,5,6,7}
CollectionUtils.intersection(a, b)(交集): {3,4,5}
CollectionUtils.disjunction(a, b)(交集的补集): {1,2,3,4,6,7}
CollectionUtils.disjunction(b, a)(交集的补集): {1,2,3,4,6,7}
CollectionUtils.subtract(a, b)(A与B的差): {1,2,3}
CollectionUtils.subtract(b, a)(B与A的差): {4,6,7}
posted on 2019-02-01 15:14 EastChilde 阅读(445) 评论(0) 编辑 收藏 举报