Hash map exception in java ClassCastException

On execution of the code, the code show you an exception indicating an string cannot be converted into double.

PROGRAM

import java.util.*;

import java.util.Iterator;

public class Hashmapexception {

public static void main(String[] args) {

HashMap hashMap = new HashMap();

hashMap.put("ABS", new Double(3434.34));

hashMap.put("ABD", new Double(123.22));

hashMap.put("cccc", "jdshgjhs");

Set set = hashMap.entrySet();

Iterator i = set.iterator();

while (i.hasNext()) {

Map.Entry me = (Map.Entry) i.next();

System.out.println(me.getKey() + " : " + me.getValue());

}

double balance = ((Double) hashMap.get("cccc")).doubleValue();

hashMap.put("cccc", new Double(balance + 1000));

System.out.println("balance : " + hashMap.get("cccc"));

}

}

OUTPUT

Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Double

at Hashmapexception.main(Hashmapexception.java:20)

Java Result: 1