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Kuidas on organiseeritud kogude struktuur ja kuidas nad on omavahel seotud?

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In Android (and generally in Java), collections are organized in a hierarchy of interfaces and classes that provide storage and management of groups of objects.

Main interfaces of collections:

  • Collection — the base interface for all collections.
  • List — an ordered list of elements with access by index (e.g., ArrayList, LinkedList).
  • Set — a collection of unique elements (e.g., HashSet, TreeSet).
  • Queue — a collection for storing elements in processing order (e.g., LinkedList, PriorityQueue).

Additionally, there is the Map interface, which does not inherit from Collection but is related to collections — it stores key-value pairs (e.g., HashMap, TreeMap).

Relationship between them:

  • List, Set, and Queue extend Collection.
  • Map is a separate structure for key-value pairs.

Example: ArrayList implements List, which extends Collection, so ArrayList can be used as both a Collection and a List.

This structure allows choosing the appropriate collection depending on requirements for uniqueness, order, and access method to elements.