Collection در جاوا

• to store n number of data we can use arrays. but there are some problem in array: 1-array is a fixed length 2-type is defined and fixed and we can not store different data types. 3-the operations like insertion and deletion are very difficult.
• java provides Collection interface. Collection is an interface in java.util package
• collection has 4 sub interfaces:
• 1-set: set has 2 classes hash set and linked hash set.
• 2-List{Array list, linked list, stack, vector}
• 3-Queue
• 4-map{hash table, hash map}
• set is an interface. we can add different type of objects to it.
  1-set doesn't support duplicate Values.
  2-the size of set is not fixed.
  3-while storing, set does not store the data in same order in which we
  have provided. hash set support null for example hs.add(null)
  4-set has 2 differents implemented class one is hash set and another is
  linked hash set.
  hash set: is support all feature of the set. it stores the data in
  array format.
  LinkedHashset: it support the feature of set but it stores the data in same order how it was been provided. it stores data in the format of link list.