WeakHashMap containsValue() Method in Java
The java.util.WeakHashMap.containsValue() method is used to check whether a particular value is being mapped by a single or more than one key in the WeakHashMap. It takes the Value as a parameter and returns True if that value is mapped by any of the key in the map.
Syntax:
Weak_Hash_Map.containsValue(Object Value)
Parameters: The method takes just one parameter Value of Object type and refers to the value whose mapping is supposed to be checked by any key inside the map.
Return Value: The method returns boolean true if the mapping of the value is detected else false.
Below programs illustrate the java.util.WeakHashMap.containsValue() Method:
Program 1: Mapping String Values to Integer Keys.
// Java code to illustrate the containsValue() method import java.util.*; public class Weak_Hash_Map_Demo { public static void main(String[] args) { // Creating an empty WeakHashMap Map<Integer, String> weak_hash = new WeakHashMap<Integer, String>(); // Mapping string values to int keys weak_hash.put( 10 , "Beginner" ); weak_hash.put( 15 , "4" ); weak_hash.put( 20 , "Beginner" ); weak_hash.put( 25 , "Welcomes" ); weak_hash.put( 30 , "You" ); // Displaying the WeakHashMap System.out.println( "Initial Mappings are: " + weak_hash); // Checking for the Value 'Beginner' System.out.println( "Is the value 'Beginner' present? " + weak_hash.containsValue( "Beginner" )); // Checking for the Value 'World' System.out.println( "Is the value 'World' present? " + weak_hash.containsValue( "World" )); } } |
Initial Mappings are: {30=You, 15=4, 10=Beginner, 25=Welcomes, 20=Beginner} Is the value 'Beginner' present? true Is the value 'World' present? false
Program 2: Mapping Integer Values to String Keys.
// Java code to illustrate the containsValue() method import java.util.*; public class Weak_Hash_Map_Demo { public static void main(String[] args) { // Creating an empty WeakHashMap Map<String, Integer> weak_hash = new WeakHashMap<String, Integer>(); // Mapping int values to string keys weak_hash.put( "Beginner" , 10 ); weak_hash.put( "4" , 15 ); weak_hash.put( "Beginner" , 20 ); weak_hash.put( "Welcomes" , 25 ); weak_hash.put( "You" , 30 ); // Displaying the WeakHashMap System.out.println( "Initial Mappings are: " + weak_hash); // Checking for the Value '10' System.out.println( "Is the value '10' present? " + weak_hash.containsValue( 10 )); // Checking for the Value '30' System.out.println( "Is the value '30' present? " + weak_hash.containsValue( 30 )); // Checking for the Value '40' System.out.println( "Is the value '40' present? " + weak_hash.containsValue( 40 )); } } |
Initial Mappings are: {Welcomes=25, 4=15, You=30, Beginner=20} Is the value '10' present? false Is the value '30' present? true Is the value '40' present? false
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
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