Hashtable contains() Method in Java Last Updated : 02 Jun, 2023 Summarize Comments Improve Suggest changes Share Like Article Like Report The java.util.Hashtable.contains(Object value) method in Java is used to check whether a particular value is being mapped by any keys present in the Hashtable. Syntax: Hash_table.contains(Object value) Parameters: The method accepts one parameter value of object type and refers to the value of the hashtable whose mapping is to be verified. Return Value: The method returns a boolean true value if the passed value is mapped by any of the keys in the Hashtable. Exceptions: The method throws NullPointerException if the passed value is Null. Below programs illustrate the working of the above-mentioned method: Program 1: Java // Java code to illustrate the contains() method import java.util.*; public class Hash_Table_Demo { public static void main(String[] args) { // Creating an empty Hashtable Hashtable<Integer, String> hash_table = new Hashtable<Integer, String>(); // Mapping string values to int keys hash_table.put(10, "Geeks"); hash_table.put(15, "4"); hash_table.put(20, "Geeks"); hash_table.put(25, "Welcomes"); hash_table.put(30, "You"); // Displaying the HashMap System.out.println("Initial Table is: " + hash_table); // Checking for the Value 'Geeks' System.out.println("Is the value 'Geeks' present? " + hash_table.contains("Geeks")); // Checking for the Value 'World' System.out.println("Is the value 'World' present? " + hash_table.contains("World")); } } Output:Initial Table is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes} Is the value 'Geeks' present? true Is the value 'World' present? false Program 2: Java // Java code to illustrate the contains() method import java.util.*; public class Hash_Table_Demo { public static void main(String[] args) { // Creating an empty Hashtable Hashtable<String, Integer> hash_table = new Hashtable<String, Integer>(); // Mapping int values to string keys hash_table.put("Geeks", 10); hash_table.put("4", 15); hash_table.put("Geeks", 20); hash_table.put("Welcomes", 25); hash_table.put("You", 30); // Displaying the Hashtable System.out.println("Initial Mappings are: " + hash_table); // Checking for the Value '10' System.out.println("Is the value '10' present? " + hash_table.containsValue(10)); // Checking for the Value '30' System.out.println("Is the value '30' present? " + hash_table.containsValue(30)); // Checking for the Value '40' System.out.println("Is the value '40' present? " + hash_table.containsValue(40)); } } Output:Initial Mappings are: {You=30, Welcomes=25, 4=15, Geeks=20} Is the value '10' present? false Is the value '30' present? true Is the value '40' present? false Comment More infoAdvertise with us Next Article HashTable forEach() method in Java with Examples C chinmoy lenka Follow Improve Article Tags : Misc Java Java-Collections Java - util package Java-HashTable +1 More Practice Tags : JavaJava-CollectionsMisc Similar Reads Hashtable in Java Hashtable class, introduced as part of the Java Collections framework, implements a hash table that maps keys to values. Any non-null object can be used as a key or as a value. 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