keyset() vs entrySet() in map

The entrySet() method is used to get a Set view of the mappings contained in this map.

The keySet() method is used to get a Set view of the keys contained in this map.

Suppose we put a string array elements is a map where elements of string array is key and frequency of word is value, e.g.:

String[] args = {"if","it","is","to","be","it","is","up","me","to","delegate"};

then the map will have entries like [ if:1 , it:2 .... ]

Set<String> keys = m.keySet();
System.out.println("keyset of the map : "+keys);

prints all keys: "if","it","is","to","be","it","is","up","me","to","delegate"

Set<Map.Entry<String, Integer>> entrySet = m.entrySet();
    Iterator<Map.Entry<String, Integer>> i = entrySet.iterator();
    while(i.hasNext()){
        Map.Entry<String, Integer> element = i.next();
        System.out.println("Key: "+element.getKey()+" ,value: "+element.getValue());
    }

prints all key values pairs :

Using entry set prints all values:

Key: if ,value: 1
Key: it ,value: 2
Key: is ,value: 2
Key: to ,value: 2
Key: be ,value: 1
Key: up ,value: 1
Key: me ,value: 1
Key: delegate ,value: 1

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Arun is a JAVA/J2EE developer and passionate about coding and managing technical team.