IdentityHashMap clear() Method in Java Last Updated : 23 Jul, 2018 Comments Improve Suggest changes Like Article Like Report The java.util.IdentityHashMap.clear() method in Java is used to clear and remove all of the elements or mappings from a specified map. Syntax: Identity_HashMap.clear() Parameters: The method does not accept any parameters. Return Value: The method does not return any value. Below programs are used to illustrate the working of java.util.IdentityHashMap.clear() Method: Program 1: Mapping String Values to Integer Keys. Java // Java code to illustrate the clear() method import java.util.*; public class Identity_Hash_Map_Demo { public static void main(String[] args) { // Creating an empty IdentityHashMap IdentityHashMap<Integer, String> identity_hash = new IdentityHashMap<Integer, String>(); // Mapping string values to int keys identity_hash.put(10, "Geeks"); identity_hash.put(15, "4"); identity_hash.put(20, "Geeks"); identity_hash.put(25, "Welcomes"); identity_hash.put(30, "You"); // Displaying the IdentityHashMap System.out.println("Initial Mappings are: " + identity_hash); // Clearing the map using clear() identity_hash.clear(); // Displaying the final IdentityHashMap System.out.println("Final Map: " + identity_hash); } } Output: Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4} Final Map: {} Program 2: Mapping Integer Values to String Keys. Java // Java code to illustrate the clear() method import java.util.*; public class Identity_Hash_Map_Demo { public static void main(String[] args) { // Creating an empty IdentityHashMap Map<String, Integer> identity_hash = new IdentityHashMap<String, Integer>(); // Mapping int values to string keys identity_hash.put("Geeks", 10); identity_hash.put("4", 15); identity_hash.put("Geeks", 20); identity_hash.put("Welcomes", 25); identity_hash.put("You", 30); // Displaying the IdentityHashMap System.out.println("Initial Mappings are: " + identity_hash); // Clearing the map using clear() identity_hash.clear(); // Displaying the final IdentityHashMap System.out.println("Final Map: " + identity_hash); } } Output: Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15} Final Map: {} Note: The same operation can be performed with any type of Mapping with variation and combination of different data types. Comment More infoAdvertise with us C chinmoy lenka Follow Improve Article Tags : Misc Java Java-Collections Java-Functions java-IdentityHashMap +1 More Practice Tags : JavaJava-CollectionsMisc Explore BasicsIntroduction to Java4 min readJava Programming Basics9 min readJava Methods7 min readAccess Modifiers in Java6 min readArrays in Java9 min readJava Strings8 min readRegular Expressions in Java7 min readOOPs & InterfacesClasses and Objects in Java10 min readJava Constructors10 min readJava OOP(Object Oriented Programming) Concepts10 min readJava Packages7 min readJava Interface11 min readCollectionsCollections in Java12 min readCollections Class in Java13 min readCollection Interface in Java6 min readIterator in Java5 min readJava Comparator Interface6 min readException HandlingJava Exception Handling8 min readJava Try Catch Block4 min readJava final, finally and finalize4 min readChained Exceptions in Java3 min readNull Pointer Exception in Java5 min readException Handling with Method Overriding in Java4 min readJava AdvancedJava Multithreading Tutorial15+ min readSynchronization in Java10 min readFile Handling in Java5 min readJava Method References9 min readJava 8 Stream Tutorial15+ min readJava Networking15+ min readJDBC Tutorial12 min readJava Memory Management4 min readGarbage Collection in Java6 min readMemory Leaks in Java3 min readPractice JavaJava Interview Questions and Answers15+ min readJava Programs - Java Programming Examples8 min readJava Exercises - Basic to Advanced Java Practice Programs with Solutions7 min readJava Quiz | Level Up Your Java Skills1 min readTop 50 Java Project Ideas For Beginners and Advanced [Update 2025]15+ min read Like