{"id":201739,"date":"2023-11-12T03:04:22","date_gmt":"2023-11-12T03:04:22","guid":{"rendered":"https:\/\/namso-gen.co\/blog\/how-to-get-key-from-value-in-hashmap\/"},"modified":"2023-11-12T03:04:22","modified_gmt":"2023-11-12T03:04:22","slug":"how-to-get-key-from-value-in-hashmap","status":"publish","type":"post","link":"https:\/\/namso-gen.co\/blog\/how-to-get-key-from-value-in-hashmap\/","title":{"rendered":"How to get key from value in HashMap?"},"content":{"rendered":"

Getting a key from a value in a HashMap in Java can be a common requirement when working with key-value pairs. While HashMap does not have a direct method to retrieve a key based on its value, there are a few ways to achieve this.<\/p>\n

One straightforward approach is to iterate through the entry set of the HashMap and check each key-value pair until the desired value is found. Once the value is matched, you can return the corresponding key.<\/p>\n

Here is an example code snippet demonstrating how to get a key from value in HashMap:<\/p>\n

“`java
\npublic static K getKeyFromValue(Map map, V value) {
\n for (Map.Entry entry : map.entrySet()) {
\n if (entry.getValue().equals(value)) {
\n return entry.getKey();
\n }
\n }
\n return null;
\n}
\n“`<\/p>\n

In this method, we iterate through the entry set of the map and compare the values against the specified value. If a match is found, we return the corresponding key. If no match is found, we return null.<\/p>\n

Now, you can use this utility method to get the key from a value in your HashMap:<\/p>\n

“`java
\nMap map = new HashMap<>();
\nmap.put(“A”, 1);
\nmap.put(“B”, 2);
\nmap.put(“C”, 3);<\/p>\n

String key = getKeyFromValue(map, 2);
\nSystem.out.println(“Key: ” + key); \/\/ Output: Key: B
\n“`<\/p>\n

This will output “Key: B” as “B” is the key for the value 2 in the HashMap.<\/p>\n

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