Demonstrate HashMap by Adding Elements

Here is a Java Program to Demonstrate HashMap

import java.util.*;

class HashMapDemo {
  public static void main(String args[]) {

    // Create a hash map
    HashMap hm = new HashMap();
    
    // Put elements to the map
    hm.put("John Doe", new Double(3434.34));
    hm.put("Tom Smith", new Double(123.22));
    hm.put("Jane Baker", new Double(1378.00));
    hm.put("Tod Hall", new Double(99.22));
    hm.put("Ralph Smith", new Double(-19.08));

    // Get a set of the entries
    Set set = hm.entrySet();

    // Get an iterator
    Iterator i = set.iterator();

    // Display elements
    while(i.hasNext()) {
      Map.Entry me = (Map.Entry)i.next();
      System.out.print(me.getKey() + ": ");
      System.out.println(me.getValue());
    }
    System.out.println();

    // Deposit 1000 into John Doe's account
    double balance =  ((Double)hm.get("John Doe")).doubleValue();
    hm.put("John Doe", new Double(balance + 1000));
    System.out.println("John Doe's new balance: " +
      hm.get("John Doe"));
  }
}

Output of Above Java Program
John Doe: 3434.34
Tom Smith: 123.22
Jane Baker: 1378.0
Tod Hall: 99.22
Ralph Smith: -19.08

John Doe's new balance: 4434.34