Dictionary keys() Method in Java with Examples

The keys() method of Dictionary class in Java is used to get the enumeration of the keys present in the dictionary.

Syntax:

Enumeration enu = DICTIONARY.keys()

Parameters: The method does not take any parameters.

Return value: The method returns an enumeration of the keys of the Dictionary.

Below programs are used to illustrate the working of the java.util.Dictionary.keys() method:
Program 1:

// Java code to illustrate the keys() method
import java.util.*;

public class Dictionary_Demo {
    public static void main(String[] args)
    {

        // Creating an empty Dictionary
        Dictionary<Integer, String> dict
            = new Hashtable<Integer, String>();

        // Inserting elements into the Dictionary
        dict.put(10, "Geeks");
        dict.put(15, "4");
        dict.put(20, "Geeks");
        dict.put(25, "Welcomes");
        dict.put(30, "You");

        // Displaying the Dictionary
        System.out.println("The Dictionary is: " + dict);

        // Creating an empty enumeration to store
        Enumeration enu = dict.keys();

        System.out.println("The enumeration of keys are:");

        // Displaying the Enumeration
        while (enu.hasMoreElements()) {
            System.out.println(enu.nextElement());
        }
    }
}

Output:

The Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The enumeration of keys are:
10
20
30
15
25

Program 2:

// Java code to illustrate the keys() method
import java.util.*;

public class Dictionary_Demo {
    public static void main(String[] args)
    {

        // Creating an empty Dictionary
        Dictionary<String, Integer> dict
            = new Hashtable<String, Integer>();

        // Inserting elements into the table
        dict.put("Geeks", 10);
        dict.put("4", 15);
        dict.put("Geeks", 20);
        dict.put("Welcomes", 25);
        dict.put("You", 30);

        // Displaying the Dictionary
        System.out.println("The Dictionary is: " + dict);

        // Creating an empty enumeration to store
        Enumeration enu = dict.keys();

        System.out.println("The enumeration of keys are:");

        // Displaying the Enumeration
        while (enu.hasMoreElements()) {
            System.out.println(enu.nextElement());
        }
    }
}

Output:

The Dictionary is: {You=30, Welcomes=25, 4=15, Geeks=20}
The enumeration of keys are:
You
Welcomes
4
Geeks