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This article introduces the relevant knowledge of "how to use the CollectionUtils tool class in java to determine whether the collection is empty". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Use the CollectionUtils utility class to determine whether the collection is empty (List is null or size () = = 0)

1. CollectionUtils.isEmpty (null): true

2. Example: List a = new ArrayList (); / / a.size () = 0

CollectionUtils.isEmpty (a): true

3. Example:

List list = new ArrayList (); list.add ("a"); list.add ("b"); System.out.println (list); / / list.size () = = 2 CollectionUtils.isEmpty (list): false determines that the set is not empty (List is not null and size ()! = 0)

1. CollectionUtils.isNotEmpty (null): false

2. Example: List a = new ArrayList (); / / a.size () = 0

CollectionUtils.isNotEmpty (a): false

3. Example:

List list = new ArrayList (); list.add ("a"); list.add ("b"); System.out.println (list); / / list.size () = = 2 CollectionUtils.isNotEmpty (list): true determines whether the collection is empty underlying public static boolean isNotEmpty (Collection coll) {return! isEmpty (coll);} public static boolean isEmpty (Collection coll) {return coll = = null | | coll.isEmpty () } Collection to determine whether the tool class (CollectionUtils) tool class org.springframework.util.CollectionUtils method / / Collection public static boolean isEmpty (Collection collection) {return collection = = null | | collection.isEmpty ();} / Map public static boolean isEmpty (Map map) {return map = = null | | map.isEmpty ();} "how to use the CollectionUtils tool class in java to determine whether the collection is empty" ends here. Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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