Collection Classes	Duplicates Accepted?	Insertion Order maintained?	Sorted Order?	Is Thread Safe?
List
ArrayList	Yes	Yes	No	No
LinkeList	Yes	Yes	No	No
Vector	Yes	Yes	No	Yes
Set
HashSet	No	No	No	No
LinkedHashSet	No	Yes	No	No
TreeSet	No	Yes	Yes	No
Map
HashMap	No	No	No	No
LinkedHashMap	No	Yes	No	No
Hashtable	No	No	No	Yes
TreeMap	No	Yes	Yes	No

• All lists allow duplicate elements and follow insertion order.
• All list elements are not sorted.
• All sets and maps do not allow duplicate elements.
• Sets and maps do not sort their elements, except TreeSet and TreeMap – in which elements are sorted by natural order or by a comparator.
• Elements within sets and maps are not ordered, except for:
  • LinkedHashSet and LinkedHashMap have elements ordered by insertion order.
  • TreeSet and TreeMap have elements ordered by natural order or by a comparator.
• There are only two collections that are thread-safe: Vector and Hashtable. The rest is not thread-safe.

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Let's meet at the other tech article next time. Until then stay connected with me on LinkedIn

-- Pasumarthi Sai Phani Krishna (aka PSPK)😊