Collections

Overview

• Grouping of an individual objects as an entity is known as collection.
• Collection framework provides the interfaces and classes for an individual object.
• The drawbacks of using arrays is taken care by collections.
• MemoryAllocation wise collections are peferable but performance wise collections are not.
• Collections are growable in nature, can hold both home and heterogenous elements unlike arrays.
• For every collection readymade method support is high.
• There are 9 interfaces of collection. collection is the root interface for collection framework.
• List(arrayList, linkedList, vector(stack))
• Set(Hashset(LinkedHashset), Sortedset(NavigableSet(TreeSet)))
• Queue(PriorityQueue, BlockingQueue(PriorityBlockingQueue(LinkedBlockingQueue)))
• Map(HashMap(LinkedHashMap), WeakedHashMap, IdentityHashMap, SortedMap(NavigableMap(TreeMap)), HashMap(Properties))
• Collection.forEach() uses collections iterator(if one is specified), so the processing order of the items is defined. In contrast, the processing order of Collection.stream().forEach is undefined.