/*
Get Set view of Keys from Java Hashtable example
This Java Example shows how to get a Set of keys contained in Hashtable
using keySet method of Java Hashtable class.
*/
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Hashtable;
import java.util.Set;
public class GetSetViewOfKeysFromHashtableExample {
public static void main(String[] args) {
//create Hashtable object
Hashtable ht = new Hashtable();
//add key value pairs to Hashtable
ht.put("1","One");
ht.put("2","Two");
ht.put("3","Three");
/*
get Set of keys contained in Hashtable using
Set keySet() method of Hashtable class
*/
Set st = ht.keySet();
System.out.println("Set created from Hashtable Keys contains :");
//iterate through the Set of keys
Iterator itr = st.iterator();
while(itr.hasNext())
System.out.println(itr.next());
/*
Please note that resultant Set object is backed by the Hashtable.
Any key that is removed from Set will also be removed from
original Hashtable object. The same is not the case with the element
addition.
*/
//remove 2 from Set
st.remove("2");
//print keys of original Hashtable
System.out.println("Hashtable keys after removal from Set are :");
Enumeration e = ht.keys();
while(e.hasMoreElements())
System.out.println(e.nextElement());
}
}
/*
Output would be
Set created from Hashtable Keys contains :
3
2
1
Hashtable keys after removal from Set are :
3
1
*/
