Re: How to cast an Object to Double?

Maybe this makes it clearer ...

public class PropertyDouble {
     public static void main(String[] args) throws FileNotFoundException,
             IOException {

         Properties states = new Properties();
         states.load(new FileInputStream("property_file.txt"));

         // copy entries from states file to the map
         Map<String, Double> map = new HashMap<String, Double>(10);
         for (Map.Entry entry : states.entrySet()) {

             Object keyObj = entry.getKey();
             if (keyObj instanceof String) {
                 System.out.println("Key is a String");
             }
             String key = (String) keyObj;

             Object valueObj = entry.getValue();
             if (valueObj instanceof String) {
                 System.out.println("Value is a String");
             }
             String valueString = (String) valueObj;
             Double value = Double.parseDouble(valueString);

             map.put(key, value);
         }

         double value = 2.54 * map.get("HAT_SIZE");
         System.out.printf("Metric : %.4f \n", value);
     }
}