![]() The HashMap can be iterated over with the forEach() method. These can be extracted from the Map.Entry using its getKey and getValue methods respectively:įor (Map.Entry entry: countryNames. The forEach() is a new method introduced in Java 8 to iterate over collections. HashMap provides constant-time performance for the. This means that it returns a set of all the keys in the hashmap that can be used to iterate through the keys or perform other operations on them. Am I doing anything wrong Is there any change I have to make Below is the code and its output. ![]() Each Map.Entry visited by the loop contains one of the keys from the map and the corresponding value. What is HashMap collection in java HashMap is Hash table based implementation of the Map interface. How to Iterate Through a Java Hashmap Using a for loop with keySet() In Java, the keySet() method is a method of the class that returns a Set view of the keys contained in the hashmap. Java HashMap 'put' method in a for loop Ask Question Asked 10 years, 3 months ago Modified 9 years, 7 months ago Viewed 9k times 2 I am facing an issue while using HashMap in a for loop. However it does provide a method named entrySet, which returns a view of the Map in the form of a Set of Map.Entry.Ī Set is a type of Collection, so can be used in an enhanced for loop. A Map is none of these, so cannot directly be used as the subject of an enhanced for loop. This technique is applicable to implementations of, other types of, and to built-in arrays. Statement is a statement to be executed for each entry in the collection, andĮlement is a variable used to refer to the current element while the iteration is in progress. (The methods described here are not specific to HashMap and can be applied to any type of Map.) MethodĪ common method for iterating over a Java collection is to use an enhanced for loop, which has the form:Ĭollection is the collection to be iterated over, ![]() You wish to list the content of this map to System.out. countryNames = new () ĬountryNames.put("AE", "United Arab Emirates") ĬountryNames.put("AG", "Antigua and Barbuda") Suppose you have a named countryNames, which contains a list of country names indexed by ISO 3166 country code: In this tutorial we will learn how to loop HashMap using following methods: For loop While loop + Iterator Example: In the below example we are iterating the HashMap using both the methods (for loop and while loop). To perform a given action for each entry of a.
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