//DatesHashsetTest.java
//demo of user class in a hash set.
//create random Dates and add to HashSet.  
//How are duplicates determined?  user class Date must override equals() and hashCode()

import java.util.*;      
import javax.swing.*;

public class DatesHashSetTest {
    public static void main(String[] args) {
	String input;
	int size;
	
	HashSet myDatesHashSet = new HashSet();

	input = JOptionPane.showInputDialog( "Enter number of random dates" );
	size = Integer.parseInt( input );

	Date randDate;
	for (int i=1; i<=size; i++) {  
	    randDate = generateRandomDate();
	    System.out.print(randDate);
	    if (myDatesHashSet.add(randDate))
		System.out.println("   Added to set!");
	    else
		System.out.println("   Duplicate already in set. Not added to set!");
	}

	Iterator it = myDatesHashSet.iterator();
	System.out.println("Here are your unique random dates in the set: ");
	while (it.hasNext())
	    System.out.print(it.next() + " ");    
	System.out.println();

	System.exit(0);
    }
  
  
    //generate a random Date
    public static Date generateRandomDate() {
	int year, month, day=0;

	//year = (int)(Math.random()*20+1995);  // +/- 10 years from 2005
	year = 2006;    //365 possible random dates...
    	month = (int)(Math.random()*12+1);
	switch (month) {
	case 1:
	case 3:
	case 5:
	case 7:
	case 8:
	case 10:
	case 12:
	    day = (int)(Math.random()*31+1);
	    break;
	case 4:
	case 6:
	case 9:
	case 11:
	    day = (int)(Math.random()*30+1);
	    break;
	case 2:
	    if (year%4==0 && year%100!=0 || year%400==0)  //leap year test
  	        day = (int)(Math.random()*29+1);
	    else
  	        day = (int)(Math.random()*28+1);
	    break;
	}    	
        return new Date(month,day,year);
    }  
}