What is Map Interface in Java ?

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Here we learn what is Map Interface In Java.

Interface Map<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

Known Subinterfaces:

ConcurrentMap<K,V>, ConcurrentNavigableMap<K,V>, NavigableMap<K,V>, SortedMap<K,V>

Known Implementing Classes:

AbstractMap, ConcurrentHashMap, EnumMap, HashMap, Hashtable, LinkedHashMap, Properties, TreeMap, WeakHashMap

Map interface belongs to java.util.* package .Map interface maps keys to values. A map cannot contain duplicate keys; each key can map to atleast one value.

Map interface takes the place of the Dictionary class, which was a totally abstract class rather than an interface.

Some map implementations, like the TreeMap class, guarantees as to their order; others, like the HashMap class do not guarantee their order.

Map interface is a member of the Java Collections Framework.

Map Interface Basic Operations

The basic operations of Map are put, get, containsKey, containsValue, size, and isEmpty.

Example Of Map interface :-

import java.util.HashMap;

import java.util.Map;

public class MapInterfaceExample {

public static void main(String[] args) {

String[] arr = {"This","is","a","map","interface","example"};

Map<String, Integer> map = new HashMap<>();

for(String str : arr){

map.put(str, 1);

}

System.out.println("MAP : "+map);

System.out.println("MAP GET() : "+map.get("a"));

System.out.println("MAP SIZE() : "+map.size());

System.out.println("MAP IS EMPTY() : "+map.isEmpty());

System.out.println("MAP CONTAINS KEY (is) : "+map.containsKey("is"));

System.out.println("MAP CONTAINS VALUE (1) : "+map.containsValue(1));

}

}

Program Output :-

MAP : {a=1, This=1, is=1, interface=1, map=1, example=1}

MAP GET() : 1

MAP SIZE() : 6

MAP IS EMPTY() : false

MAP CONTAINS KEY (is) : true

MAP CONTAINS VALUE (1) : true