Collections in Java

Collection (I) :

• A group of individual objects as a single entity.

• Collection interface defines the most common methods which are applicable for any collection object

• In general collection, interface is considered as Root Interface of collection framework

• There is no concrete class which implements Collection interface directly

Java Collections

Collection Framework: Several classes and interfaces which can be used to represent a group of objects

Following are Legacy characters present in Collection Framework:

1. Enumeration(I)
2. Dictionary(AC) [AC -> abstracct Class]
3. Vector(C)
4. Stack(C)
5. Hashtable(C)
6. Properties(C)

Collections:

• It is a utility class present in java.util package

• Collections class defines several utility methods for collection objects like sorting, searching, reversing, etc.,.

ex:     Collections.sort(al);
         Collections.reverse(al);    // where al --> arraylist

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