/* Example of Immutable Variables */
import java.util.Date;
import java.util.Calendar;
import java.io.PrintWriter;

class ImmutableVariables{
   
  public static void main(String[] args){
    PrintWriter pw = new PrintWriter(System.out, true);
    
    // Create a mutable Calendar Object
    pw.println("\n== Demonstrate mutable Calendar Object ==");
    Calendar cal = Calendar.getInstance();
    pw.println("Start Date: " + cal.getTime());
    cal.set(2010, 11, 31, 12, 00);
    pw.println("Updated Date: " + cal.getTime());
    
    // Create an immutable String Object
    pw.println("\n== Demonstrate immutable String Object ==");
    String start = "Start String";
    pw.println("start =  " + start);
    start.replaceAll("Start", "Updated");
    pw.println("start =  " + start);
    
    // Change the String Reference
    pw.println("\n== Copy String and Compare it ==");
    pw.println("start = " + start);
    String copy = start;
    pw.println("String contents equal: " + copy.equals(start));
    pw.println("String reference equal: " + (copy == start));
    
    pw.println("\n== Change Copy and Compare Strings ==");
    start = new String("Start String"); 
    pw.println("start = " + start);
    pw.println("String contents equal: " + copy.equals(start));
    pw.println("String reference equal: " + (copy == start) + "\n");    
    
  }
}