Java AbstractMap hashCode() Method Last Updated : 20 Jan, 2025 Comments Improve Suggest changes Like Article Like Report The hashCode() method of the AbstractMap class in Java is used to calculate a hash code value for a map. This hash code is based on the key-value mapping contained in the map. It ensures consistency such that two maps with the same entries have the same hash code.Example 1: Hash Code of a Non-Empty Map Java // Java program demonstrate the working of hashCode() import java.util.AbstractMap; import java.util.HashMap; import java.util.Map; public class Geeks { public static void main(String[] args) { // Create a HashMap Map<String, Integer> hm = new HashMap<>(); // Add key-value pairs hm.put("Java", 1); hm.put("Programnming", 2); hm.put("Language", 3); // Get hashCode System.out.println("Map: " + hm); System.out.println("HashCode: " + hm.hashCode()); } } OutputMap: {Programnming=2, Java=1, Language=3} HashCode: -95421541 Explanation: In the above example, it creates a HashMap and adds three key-value pairs to it. The hashCode() method calculates a unique integer value based on the keys and values in the map.Syntax of AbstractMap hashCode() Methodpublic int hashCode()Return Type: It returns an integer representing the hash code value of the map.Example 2: Hash Code of an Empty Map Java // Java programm to demonstrates the // hash code of an empty HashMap import java.util.AbstractMap; import java.util.HashMap; import java.util.Map; public class Geeks { public static void main(String[] args) { // creating an empty HashMap Map<String, Integer> hm1 = new HashMap<>(); System.out.println("Empty Map: " + hm1); System.out.println("HashCode of Empty Map: " + hm1.hashCode()); } } OutputEmpty Map: {} HashCode of Empty Map: 0 Explanation: The above program creates an empty HashMap without any key-value pairs. The hashCode() method returns 0 because no entries exist in the map. Comment More infoAdvertise with us Next Article Java AbstractMap hashCode() Method chinmoy lenka Follow Improve Article Tags : Misc Java Java-Collections Java - util package Java-Functions Java-HashMap Java-AbstractMap +3 More Practice Tags : JavaJava-CollectionsMisc Similar Reads HashMap in Java In Java, HashMap is part of the Java Collections Framework and is found in the java.util package. It provides the basic implementation of the Map interface in Java. HashMap stores data in (key, value) pairs. Each key is associated with a value, and you can access the value by using the corresponding 15+ min read HashMap clear() Method in Java The clear() method of the HashMap class in Java is used to remove all of the elements or mappings (key-value pairs) from a specified HashMap.Example 2: Here, we will use the clear() method to clear a HashMap of Integer keys and String values. 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