Set, List together with Map are 3 of import interfaces of Java collection framework together with Difference betwixt Set, List, together with Map inwards Java is ane of the close oft asked Java Collection interview question. Sometimes this enquiry is asked every bit When to usage List, Set together with Map inwards Java. Clearly, the interviewer is looking to know that whether you lot are familiar alongside fundamentals of Java collection framework or not. In gild to determine when to usage List, Set or Map, you lot demand to know what are these interfaces together with what functionality they provide. List inwards Java provides ordered together with indexed collection which may comprise duplicates.
The Set interface provides an unordered collection of unique objects, i.e. Set doesn't allow duplicates, spell Map provides a information construction based on key-value duo together with hashing.
All 3 List, Set, together with Map are interfaces inwards Java together with at that topographic point are many concrete implementations of them are available inwards Collection API. ArrayList together with LinkedList are ii close pop used List implementation spell LinkedHashSet, TreeSet, together with HashSet are oft used Set implementation.
In this Java article, nosotros volition run into the difference betwixt Map, Set, together with List inwards Java together with larn when to usage List, Set or Map.
The Set interface provides an unordered collection of unique objects, i.e. Set doesn't allow duplicates, spell Map provides a information construction based on key-value duo together with hashing.
All 3 List, Set, together with Map are interfaces inwards Java together with at that topographic point are many concrete implementations of them are available inwards Collection API. ArrayList together with LinkedList are ii close pop used List implementation spell LinkedHashSet, TreeSet, together with HashSet are oft used Set implementation.
In this Java article, nosotros volition run into the difference betwixt Map, Set, together with List inwards Java together with larn when to usage List, Set or Map.
Set vs List vs Map inwards Java
As I said Set, List together with Map are interfaces, which defines essence contract e.g. a Set contract says that it tin non comprise duplicates. Based on our cognition of List, Set together with Map let's compare them on dissimilar metrics.
Duplicate Objects
The psyche departure betwixt List together with Set interface inwards Java is that List allows duplicates spell Set doesn't allow duplicates. All implementation of Set laurels this contract.
While a Map holds ii objects per Entry e.g. a key together with a value together with It may comprise duplicate values simply keys are e'er unique. See here for to a greater extent than departure betwixt List together with Set information construction inwards Java.
While a Map holds ii objects per Entry e.g. a key together with a value together with It may comprise duplicate values simply keys are e'er unique. See here for to a greater extent than departure betwixt List together with Set information construction inwards Java.
Another key departure betwixt List together with Set is that List is an ordered collection, List's contract maintains insertion gild or element. Set is an unordered collection, you lot acquire no guarantee on which gild chemical component volition live on stored.
Though around of the Set implementation e.g. LinkedHashSet maintains order. Also SortedSet together with SortedMap e.g. TreeSet together with TreeMap maintain a sorting order, imposed past times using Comparator or Comparable.
Though around of the Set implementation e.g. LinkedHashSet maintains order. Also SortedSet together with SortedMap e.g. TreeSet together with TreeMap maintain a sorting order, imposed past times using Comparator or Comparable.
Hashtable doesn't allow nada key or values simply HashMap allows nada values together with ane nada key. This is too the psyche departure betwixt these ii pop implementations of Map interface, aka HashMap vs Hashtable.
Useful implementations
Most pop implementations of List interface inwards Java are ArrayList, LinkedList, together with Vector class. ArrayList is to a greater extent than full general purpose together with provides random access alongside index, spell LinkedList is to a greater extent than suitable for oft adding together with removing elements from List.
Vector is synchronized counterpart of ArrayList. On the other hand, close pop implementations of the Set interface are HashSet, LinkedHashSet, together with TreeSet. First ane is full general purpose Set which is backed past times HashMap, run into how HashSet plant internally inwards Java for to a greater extent than details.
It too doesn't render whatever ordering guarantee simply LinkedHashSet does render ordering along alongside uniqueness offered past times the Set interface.
Third implementation TreeSet is too an implementation of SortedSet interface, therefore it keeps elements inwards a sorted gild specified past times compare() or compareTo() method.
Now the final one, close pop implementation of Map interface is HashMap, LinkedHashMap, Hashtable, together with TreeMap.
First ane is the non-synchronized full general purpose Map implementation spell Hashtable is its synchronized counterpart, both doesn' render whatever ordering guarantee which comes from LinkedHashMap. Just similar TreeSet, TreeMap is too a sorted information construction together with keeps keys inwards sorted gild (see ArrayList provides faster access if you lot know index.
Most pop implementations of List interface inwards Java are ArrayList, LinkedList, together with Vector class. ArrayList is to a greater extent than full general purpose together with provides random access alongside index, spell LinkedList is to a greater extent than suitable for oft adding together with removing elements from List.
Vector is synchronized counterpart of ArrayList. On the other hand, close pop implementations of the Set interface are HashSet, LinkedHashSet, together with TreeSet. First ane is full general purpose Set which is backed past times HashMap, run into how HashSet plant internally inwards Java for to a greater extent than details.
It too doesn't render whatever ordering guarantee simply LinkedHashSet does render ordering along alongside uniqueness offered past times the Set interface.
Third implementation TreeSet is too an implementation of SortedSet interface, therefore it keeps elements inwards a sorted gild specified past times compare() or compareTo() method.
Now the final one, close pop implementation of Map interface is HashMap, LinkedHashMap, Hashtable, together with TreeMap.
First ane is the non-synchronized full general purpose Map implementation spell Hashtable is its synchronized counterpart, both doesn' render whatever ordering guarantee which comes from LinkedHashMap. Just similar TreeSet, TreeMap is too a sorted information construction together with keeps keys inwards sorted gild (see ArrayList provides faster access if you lot know index.
2) If you lot desire to shop elements together with desire them to maintain an order on which they are inserted into a collection so boot the bucket for List again, every bit List is an ordered collection together with maintain insertion order.
3) If you lot desire to practise a collection of unique elements together with don't desire whatever duplicate than choosing whatever Set implementation e.g. HashSet, LinkedHashSet or TreeSet.
All Set implementation follow at that topographic point full general contract e.g. uniqueness simply too add together improver characteristic e.g. TreeSet is a SortedSet together with elements stored on TreeSet tin live on sorted past times using Comparator or Comparable inwards Java. LinkedHashSet also maintains insertion order.
All Set implementation follow at that topographic point full general contract e.g. uniqueness simply too add together improver characteristic e.g. TreeSet is a SortedSet together with elements stored on TreeSet tin live on sorted past times using Comparator or Comparable inwards Java. LinkedHashSet also maintains insertion order.
4) If you lot shop information inwards shape of key together with value than Map is the agency to go. You tin direct from Hashtable, HashMap, TreeMap based upon your subsequent need. In gild to direct betwixt outset ii run into the difference betwixt HashSet together with HashMap inwards Java.
That's all on the difference betwixt Set, List, together with Map inwards Java. All 3 are the close cardinal interface of Java Collection framework together with whatever Java developer should know at that topographic point distinguish characteristic together with given a province of affairs should live on able to selection correct Collection shape to use. You tin too farther see, When to usage Vector or ArrayList etc. Collection API is huge together with it's hard to know every bits together with slice simply at the same time, at that topographic point is no excuse for non knowing fundamentals similar the departure betwixt Set, List, together with Map inwards Java.
Further Learning
Java In-Depth: Become a Complete Java Engineer
Java Fundamentals: Collections
Data Structures together with Algorithms: Deep Dive Using Java
Further Learning
Java In-Depth: Become a Complete Java Engineer
Java Fundamentals: Collections
Data Structures together with Algorithms: Deep Dive Using Java
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