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() methodimport 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() methodimport 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
