Hashtable containsKey() Method in Java
Last Updated :
28 Jun, 2018
The java.util.Hashtable.containsKey() method is used to check whether a particular key is present in the Hashtable or not. It takes the key element as a parameter and returns True if that element is present in the table.
Syntax:
Hash_table.containsKey(key_element)
Parameters: The method takes just one parameter key_element which refers to the key whose presence is supposed to be checked inside a Hashtable.
Return Value: The method returns boolean true if the key is present in the Hashtable otherwise it returns false.
Below programs are used to illustrate the working of java.util.Hashtable.containsKey() Method:
Program 1:
import java.util.*;
public class Hash_Table_Demo {
public static void main(String[] args)
{
Hashtable<Integer, String> hash_table =
new Hashtable<Integer, String>();
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" );
System.out.println( "Initial Table is: " + hash_table);
System.out.println( "Is the key '20' present? " +
hash_table.containsKey( 20 ));
System.out.println( "Is the key '5' present? " +
hash_table.containsKey( 5 ));
}
}
|
Output:
Initial Table is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Is the key '20' present? true
Is the key '5' present? false
Program 2:
import java.util.*;
public class Hash_Table_Demo {
public static void main(String[] args)
{
Hashtable<String, Integer> hash_table=
new Hashtable<String, Integer>();
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 );
System.out.println( "Initial Table is: " + hash_table);
System.out.println( "Is the key 'Welcomes' present? " +
hash_table.containsKey( "Welcomes" ));
System.out.println( "Is the key 'World' present? " +
hash_table.containsKey( "World" ));
}
}
|
Output:
Initial Table is: {You=30, Welcomes=25, 4=15, Geeks=20}
Is the key 'Welcomes' present? true
Is the key 'World' present? false
Note: The same operation can be performed with any type of variation and combination of different data types.
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