How do you check if a map contains a value in Java?

Generally if there is no collision in the hashing value of the key then the complexity of the the containskey is O(1) . The complexity can be understood by seeing how the method has been implemented. The Hashmap contains array of nodes.

HashMap. size() method of HashMap class is used to get the size of the map which refers to the number of the key-value pair or mappings in the Map. Parameters: The method does not take any parameters. Return Value: The method returns the size of the map which also means the number of key-value pairs present in the map.

Create an iterator to iterate over the HashMap using HashMap. iterate() method.

Create an iterator to iterate over the HashMap using HashMap. iterate() method.

We can also initialize the map using the double-brace syntax: Map<String, String> doubleBraceMap = new HashMap<String, String>() {{ put(“key1”, “value1”); put(“key2”, “value2”); }};