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preface In learning, we often use the List collection and Array to operate a certain number of element objects, and the Collections collection tool class contains some static methods to sort, exchange, find and other operations of the collection. This paper mainly describes the two implementation methods of Comparable and Comparator. The ...

Collection object set types are also used to hold multiple string elements Unlike list types, duplicate elements are not allowed in a collection, and elements in a collection are out of order and cannot be retrieved through an index subscript A collection can store up to 232-1 elements Redis not only supports addition, deletion, and censo ...

Dart's basic built-in type in programming Dart supports the following built-in types: NumberStringBooleanList (also known as Array)MapSetRune (used to represent Unicode characters in strings)Symbol These types can be initialized to literals. For example,'this is a string'is a literal quantity of a string, and true is a Boolean literal quan ...

1, Map interface description Store double column data and key value pair data -- similar to functions in high school Understanding of Map structure: Keys in Map: unordered and non repeatable. Use Set to store all keys - > the class where the key belongs is required to override the equals() method and hashCode() method Value in Map: an ...