[hardwired]

Code:

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class CalendarToStringTest {
    public static void main(String[] args) {
        Calendar calendar = Calendar.getInstance();
        Date now = calendar.getTime();
        System.out.println("now = " + now);
        CalendarToString ctsDefault = new CalendarToString();
        System.out.println("ctsDefault(now)      = " + ctsDefault.transform(now));
        System.out.println("ctsDefault(calendar) = " +
                            ctsDefault.transform(calendar));
        CalendarToString ctsMedium = new CalendarToString(DateFormat.MEDIUM);
        System.out.println("ctsMedium(now)       = " + ctsMedium.transform(now));
        System.out.println("ctsMedium(calendar)  = " +
                            ctsMedium.transform(calendar));
        // Test IllegalArgumentException.
        new CalendarToString().transform("hello world");
    }
}

    /**
     * Transform strategy object used to transform a <code>Calendar</code> instance
     * to a <code>String</code>.  This class uses the <code>java.text.DateFormat</code>
     * to provide the formatting.
     * 
     * The overriden method <code>transform(Object target)</code> accepts a <code>java.util.Calendar</code>
     * or <code>java.util.Date</code>object representing the date to be transformed.
     * RuntimeExceptions will be thrown when any other argument is passed to the method.
     * 
     * Classes that implement the <code>TransformStrategy</code> interface should be 
     * passed to <code>Transformer</code> objects via their constructor or to the 
     * <code>Transformer.transform(TransformStrategy, Object)</code> method.
     * 
     * @see Transformer
     * @see TransformStrategy
     */
class CalendarToString implements TransformStrategy {
    private DateFormat df;

    /**
     * Constructs a new strategy object using the specified format for its
     * transform rule.
     * 
     * @param format format to be used by this transfrom strategy
     * @see java.text.DateFormat
     */
    public CalendarToString(int format) {
        df = DateFormat.getDateInstance(format);
    }

    /**
     * Constructs a new strategy object using the default format DateFormat.FULL for its 
     * transform rule.
     */
    public CalendarToString() {
        df = DateFormat.getDateInstance(DateFormat.FULL);
        //df = new SimpleDateFormat("dd-MMM-yy");
    }

    /** 
     * Returns the specified argument <code>Calendar<code> instance as a string
     * 
     * @param target <code>Calendar</code> instance to transform
     * @return formatted string representing the <code>Calendar</code> instance
     * 
     */
    public Object transform(Object target) {
        String parsed = null;
        if(target instanceof Date)
            parsed = df.format((Date)target);
        else if(target instanceof Calendar)
            parsed = df.format(((Calendar)target).getTime());
        else
            throw new IllegalArgumentException("CalendarToString.transform for: " +
                                                target.getClass().getName());

        return parsed;
    }
}

interface TransformStrategy {
    public Object transform(Object o);
}