What is Map.Entry In Java ?

Previously we have discussed about

What is IdentityHashMap In Java ?

Here we know about Map.Entry in Java, but before that we must know What is Map Interface in Java ? and What is Collection Interface in Java ?

Interface Map.Entry<K,V>

All Known Implementing Classes:

AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

Enclosing interface:

Map<K,V>

Declaration of Map.Entry:

public static interface Map.Entry<K,V>

Map.Entry interface enables you to work with a map entry. This interface help us to iterate over Map classes.The entrySet( ) method declared by the Map interface returns a Set containing the map entries.Each of these set elements is a Map.Entry object.

JDK 8 adds two static methods. The first is comparingByKey( ), which returns a Comparator that compares entries by key. The second is comparingByValue( ), which returns a Comparator that compares entries by value.

Method Summary of Map.Entry:

Modifier and Method Name	Description
boolean equals(Object o)	Compares the specified object with this entry for equality.
K getKey()	Returns the key corresponding to this entry.
V getValue()	Returns the value corresponding to this entry.
int hashCode()	Returns the hash code value for this map entry.
V setValue(V value)	Replaces the value corresponding to this entry with the specified value (optional operation).

      
Example of Map.Entry:

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MapEntryExample {

public static void main(String[] args) {
HashMap<String, Integer> map = new HashMap<String, Integer>();
map.put("India", 100);
map.put("Japan", 101);
map.put("Russia", 103);
map.put("USA", 105);
map.put("UK", 108);

System.out.println("Map Size() : "+map.size());

System.out.println("\nAccessing Map through Iterator : ");
Iterator itr = map.entrySet().iterator();
while(itr.hasNext()){
Map.Entry me = (Map.Entry)itr.next();
System.out.println(me.getKey()+"\t"+me.getValue());
}

System.out.println("\nAccessing Map through forEach : ");
for(Map.Entry en : map.entrySet()){
System.out.println(en.getKey()+"\t"+en.getValue());
}

}


}

Program Output:

Map Size() : 5

Accessing Map through Iterator :
USA 105
Japan 101
UK 108
India 100
Russia 103

Accessing Map through forEach :
USA 105
Japan 101
UK 108
India 100
Russia 103

Blog Author - Pushkar Khosla,
Software Developer by Profession with 3.0 Yrs of Experience , through this blog i'am sharing my industrial Java Knowledge to entire world. For any question or query any one can comment below or mail me at pushkar.itsitm52@gmail.com.

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