/*
 * public static String getProperty(String key, String
 *                                               def)
 * 
 * Parameters: 
 * ----------
 * 
 * key - the name of the system property.  
 * def - a default value.
 */

public class PropertiesDemo
{

    public static void main(String[] args)
    {
        /*
         * Gets the system property indicated by the
         * specified key.if not present it will return
         * default value.
         */
        String value1 = System.getProperty("a.b", "hello");
        System.out.println("value1 = " + value1);

        
        String value2 = System.getProperty("os.name", "hello");
        System.out.println("value2 = " + value2);
        
    }
}

value1 = hello
value2 = Windows 7