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