Hashtable in java

// Demonstrate a Hashtable 
import java.util.*; 
class HTDemo { 
public static void main(String args[]) { 
Hashtable balance = new Hashtable(); 
Enumeration names; 
String str; 
double bal; 
balance.put("John Doe", new Double(3434.34)); 
balance.put("Tom Smith", new Double(123.22)); 
balance.put("Jane Baker", new Double(1378.00)); 
balance.put("Todd Hall", new Double(99.22)); 
balance.put("Ralph Smith", new Double(-19.08)); 
// Show all balances in hash table. 
names = balance.keys(); 
while(names.hasMoreElements()) { 
str = (String) names.nextElement(); 
System.out.println(str + ": " + 
balance.get(str)); 
} 
System.out.println(); 
// Deposit 1,000 into John Doe's account 
bal = ((Double)balance.get("John Doe")).doubleValue(); 
balance.put("John Doe", new Double(bal+1000)); 
System.out.println("John Doe's new balance: " + 
balance.get("John Doe")); 
} 
}