lotto program using sets

[leoshiner]

Hi I am writing a java program that will generate 100 lottery tickets store this data,then you can enter the winning lottery numbers and it will allow you to check if you have won the jackpot and also allow you to check to see if any of your numbers have come up.I have run into a problem trying to write a method to check if one or more numbers have won this is the method I have written but I am getting an error message:

Exception in thread "main" java.lang.ClassCastException: java.util.HashSet cannot be cast to java.lang.Comparable
	at java.util.TreeMap.getEntry(TreeMap.java:325)
	at java.util.TreeMap.containsKey(TreeMap.java:209)
	at java.util.TreeSet.contains(TreeSet.java:217)
	at practical3_lottery.Practical3_Lottery.checkTicket
	at practical3_lottery.Practical3_Lottery.main

The method I have written is this any help would be greatly appreciated

    public static void checkTicket(ArrayList<Ticket> list, Set<Integer> d) {


        int i = 0;


        for (Ticket x : list) {

            if (x.getticketNumbers().contains(d)) {


                System.out.println("you have at least one number");


            }

[leoshiner]

I have figured it out by using removeAll instead

[pbrockway2]

Please use the code tags when posting code. BB Code List - Java Programming Forum

It would also help to post a bit more code. Specifically people will read that fragment and wonder: so, what type of thing does getticketNumbers() return? and is that if condition the line of code indicated by the error message?

if (x.getticketNumbers().contains(d)) {
    System.out.println("you have at least one number");

The message suggests you are searching for a number within the treeset of ticket numbers. But what you send to contains() is a hashset of numbers. The ticket contains numbers not sets of numbers. (The runtime error occurs because sets of numbers are not comparable things, and sorted sets compare things in order to find elements.)

To find if at least one element of d is also an element of x.getticketNumbers() consider using a for loop and checking number in d. There may be other ways, but this seems to be the most straight forward.