Hashtable keySet() Método en Java con ejemplos

Java.util.Hashtable se utiliza para crear un conjunto de elementos clave en la tabla hash.

Sintaxis:

public Set<K> keySet()

K : tipo de Claves en la tabla hash

Parámetros: El método no toma ningún parámetro.

Valor devuelto: el método devuelve un conjunto que tiene las claves de la tabla hash.

Los siguientes programas se utilizan para ilustrar el funcionamiento del método java.util.Hashtable.keySet():
Ejemplo 1: 
 

// Java code to illustrate the keySet() method
// to get Set view of Keys from a Hashtable.
  
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Hashtable;
import java.util.Set;
  
public class Example1 {
  
    public static void main(String[] args)
    {
  
        // Creating an empty Hashtable
        Hashtable<String, String> hash_t
            = new Hashtable<String, String>();
  
        // Add mappings into the table
        hash_t.put("1", "Geeks");
        hash_t.put("2", "For");
        hash_t.put("3", "Geeks");
  
        // Getting a Set of keys using
        // keySet() method of Hashtable class
        Set hash_set = hash_t.keySet();
  
        System.out.println(
            "Set created from Hashtable Keys contains :");
  
        // Iterating through the Set of keys
        Iterator itr = hash_set.iterator();
        while (itr.hasNext())
            System.out.println(itr.next());
    }
}

Set created from Hashtable Keys contains :
3
2
1

Ejemplo 2:

// Java code to illustrate the keySet() method
// to get Set view of Keys from a Hashtable.
  
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Hashtable;
import java.util.Set;
  
public class Example2 {
  
    public static void main(String[] args)
    {
  
        // Creating an empty Hashtable
        Hashtable<String, String> hash_t
            = new Hashtable<String, String>();
  
        // Inserting elements into the table
        hash_t.put("Geeks", "1");
        hash_t.put("For", "2");
        hash_t.put("geeks", "3");
  
        // Getting a Set of keys using
        // keySet() method of Hashtable class
        Set hash_set = hash_t.keySet();
  
        System.out.println(
            "Set created from Hashtable Keys contains :");
  
        // Iterating through the Set of keys
        Iterator itr = hash_set.iterator();
        while (itr.hasNext())
            System.out.println(itr.next());
    }
}

Set created from Hashtable Keys contains :
For
Geeks
geeks

 Nota: