I want to Create Java Hashtable from HashMap.
HashMap hMap = new HashMap();
//populate HashMap
hMap.put("1","One");
hMap.put("2","Two");
hMap.put("3","Three");
//create new Hashtable
Hashtable ht = new Hashtable();
//populate Hashtable
ht.put("1","This value would be REPLACED !!");
ht.put("4","Four");
After this what will be the easiest procedure?
Use the Hashtable constructor that accepts a Map :
public Hashtable(Map<? extends K, ? extends V> t)
And also you should favor generic types on raw types and program by interface as you declare your Map instances:
Map<String,String> hMap = new HashMap<>();
//populate HashMap
hMap.put("1","One");
hMap.put("2","Two");
hMap.put("3","Three");
//create new Hashtable
Map<String,String> ht = new Hashtable<>(hMap);
Enumeration is as outdated as Hashtable , but if you really need it, use the Collections.enumeration bridge, e.g. instead of hashtable.keys(), you can use Collections .enumeration(map.keySet()) and instead of hashtable.elements(), you can use Collections.enumeration(map.values()). But normally you use an Iterator or just a for-each loop, for(String key: map.keySet()) … or for(String value: map.values()) …Whoomp!! I have done successfully.. here it is :)
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.HashMap;
public class CreateHashtableFromHashMap {
public static void main(String[] args) {
//create HashMap
HashMap hMap = new HashMap();
//populate HashMap
hMap.put("1","One");
hMap.put("2","Two");
hMap.put("3","Three");
//create new Hashtable
Hashtable ht = new Hashtable();
//populate Hashtable
ht.put("1","This value would be REPLACED !!");
ht.put("4","Four");
//print values of Hashtable before copy from HashMap
System.out.println("hastable contents displaying before copy");
Enumeration e = ht.elements();
while(e.hasMoreElements())
System.out.println(e.nextElement());
ht.putAll(hMap);
//Display contents of Hashtable
System.out.println("hashtable contents displaying after copy");
e = ht.elements();
while(e.hasMoreElements())
System.out.println(e.nextElement());
}
}
Hashtable ht = new Hashtable(hMap);orht.putAll(hMap);. Use the API documentation. Also, you should use generics and not use raw types.Hashtable?