boolean containsKey(key_element)

// Java code to illustrate
// the containsKey() method
  
import java.util.*;
  
public class Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty SortedMap
        SortedMap<Integer, String> map
            = new TreeMap<Integer, String>();
  
        // Mapping string values to int keys
        map.put(10, "Geeks");
        map.put(15, "4");
        map.put(20, "Geeks");
        map.put(25, "Welcomes");
        map.put(30, "You");
  
        // Displaying the SortedMap
        System.out.println(
            "Initial Mappings are: "
            + map);
  
        // Checking for the key_element '20'
        System.out.println("Is the key '20' present? "
                           + map.containsKey(20));
  
        // Checking for the key_element '5'
        System.out.println("Is the key '5' present? "
                           + map.containsKey(5));
    }
}

Initial Mappings are:
 {10=Geeks, 15=4, 20=Geeks, 25=Welcomes, 30=You}
Is the key '20' present? true
Is the key '5' present? false

// Java code to illustrate
// the containsKey() method
  
import java.util.*;
  
public class Map_Demo {
    public static void main(String[] args)
    {
  
        // Creating an empty SortedMap
        SortedMap<String, Integer> map
            = new TreeMap<String, Integer>();
  
        // Mapping int values to string keys
        map.put("Geeks", 10);
        map.put("4", 15);
        map.put("Geeks", 20);
        map.put("Welcomes", 25);
        map.put("You", 30);
  
        // Displaying the Map
        System.out.println(
            "Initial Mappings are: "
            + map);
  
        // Checking for the key_element 'Welcomes'
        System.out.println(
            "Is the key 'Welcomes' present? "
            + map.containsKey("Welcomes"));
  
        // Checking for the key_element 'World'
        System.out.println(
            "Is the key 'World' present? "
            + map.containsKey("World"));
    }
}

Initial Mappings are: {4=15, Geeks=20, Welcomes=25, You=30}
Is the key 'Welcomes' present? true
Is the key 'World' present? false