What is EntrySet View
Answer: entrySet view is method in HashMap class and its signature is below:
public Set<Map.Entry<K,V>> entrySet()
- This method returns Set view of mappings that is contained in the map
- Set is backed by map, so changes to the map are reflected in the set and vice-versa
- During iteration through Set if map is modified then results of the iteration are undefined
- Set also supports removal of elements using Iterator.removeAll, retainAll, remove, Set.remove and clear operation. It don’t support addAll and add method
Example of entrySet:
package com.javahonk.hashsettest; import java.util.HashMap; import java.util.Map; import java.util.Set; public class EntrySetTest { public static void main(String[] args) { Map<String, Double> empMap = new HashMap<String, Double>(); empMap.put("Java Honk", new Double(4000.55)); empMap.put("Bob Marley", new Double(3000.33)); empMap.put("Mike Musan", new Double(1378.00)); // Print set of entries. Set<Map.Entry<String, Double>> set = empMap.entrySet(); // Display it for (Map.Entry<String, Double> me : set) { System.out.print(me.getKey() + ": "); System.out.println(me.getValue()); } System.out.println(); // Withdrawn 500 by Java Honk double balance = empMap.get("Java Honk"); empMap.put("John Doe", balance - 500); System.out.println("Java Honk total balance: " + empMap.get("John Doe")); } }
Output:
