Comparing array entries

Question

So I'm extremely rusty with my java programming. I'm trying to create a hypothetical company lottery where each employee can only enter once. Then a name will be randomly generated announcing the winner. I'm not even sure I have some things in the right order at the moment. Any help on this will be greatly appreciated. I looked up some things and I believe it to have made it worse.

        // instance variables
        final int NUM_PARTIC = 7;  // number of workers participating
        String input;  // holds each name
        int i, j;

        // Create array to hold number of particpants.
        String[] nameArray = new String[NUM_PARTIC];
        // Create a Random class object.
        Random stakes = new Random();

        for(i = 0; i < nameArray.length; i++)
        {
            // Prompt participant for name.
            input = JOptionPane.showInputDialog(null, "Please enter your"
                    + " name into our database:", "Entry", JOptionPane.QUESTION_MESSAGE);
            nameArray[i] = input;  // Store name in namesArray[]

            // Prompt next participant for name
            input = JOptionPane.showInputDialog(null, "Please enter your name into our"
                    + " database:", "Entry", JOptionPane.QUESTION_MESSAGE);
            nameArray[i] = input;  // Store name in namesArray[]

            for(j = i + 1; j < nameArray.length; ++j)
            {
                JOptionPane.showMessageDialog(null, "Sorry, this name is already "
                        + "in our database", "Invalid", JOptionPane.ERROR_MESSAGE);
                input = JOptionPane.showInputDialog(null, "Please enter your name into our"
                        + " database:", "Entry", JOptionPane.QUESTION_MESSAGE);
            }

            // Display winner
            JOptionPane.showMessageDialog(null, "The winner for today's raffle "
                    + "is: " + nameArray[i], "Winner",
                    JOptionPane.WARNING_MESSAGE);

            // Exit program
            System.exit(0);

You'll need to ask a concrete question before anyone can help you. What is currently going wrong, or what part do you not know how to do? — Peaches491
– Peaches491, Commented Jun 4, 2013 at 20:02
Why you using Array? use Set as it won't accept duplicates. And it is easy to iterate over them. — Murali
– Murali, Commented Jun 4, 2013 at 20:06

Dariusz · Accepted Answer · 2013-06-04 20:04:19Z

1

What do you think you're doing in the code below? It's certainly not searching previous entries. Please speak to yourself and say what you are doing, then say what you want to do, then compare these two answers.

for(j = i + 1; j < nameArray.length; ++j)
{
  JOptionPane.showMessageDialog(null, "Sorry, this name is already "
                + "in our database", "Invalid", JOptionPane.ERROR_MESSAGE);
  input = JOptionPane.showInputDialog(null, "Please enter your name into our"
                    + " database:", "Entry", JOptionPane.QUESTION_MESSAGE);
}

Besides: just use a List<String> instead of String[].

To get a random winner just use Random class with it nextInt(nameArray.length) method.

answered Jun 4, 2013 at 20:04

Dariusz

22.5k9 gold badges81 silver badges116 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Clinton Scott Over a year ago

I'll try these out. Totally forgot about using a list for this. It makes perfect sense. Thank you people. I am basically starting programming as I have only done java 1 and 2 about a year ago. This helps.

pinkpanther · Accepted Answer · 2013-06-04 20:02:35Z

0

Use java.util.Random class for randomly selecting a winner from nameArray

Random rand=new Random()

int winnerIndex=rand.nextInt(nameArray.length);

then

JOptionPane.showMessageDialog(null, "The winner for today's raffle "
                    + "is: " + nameArray[winnerIndex], "Winner",
                    JOptionPane.WARNING_MESSAGE);

answered Jun 4, 2013 at 20:02

pinkpanther

4,8083 gold badges41 silver badges63 bronze badges

Comments

greedybuddha · Accepted Answer · 2013-06-04 20:10:36Z

0

All java collections have the contains method which searches that collection for the given item. This would be much preferable to searching an array.

In this case the best would be the Java collection Set which allows O(1) (aka very fast searches) for the same element, or just use a List if you want to be able to retrieve arbitrary elements like the array. Either way the method to find an element is done for you.

If you have to do this inside of an Array. You will need to iterate over the array.

public static boolean contains(String[] array, String search){
    for (String s: array){
        if (s.equals(search))
            return true;
    }
    return false;
}

edited Jun 4, 2013 at 20:10

answered Jun 4, 2013 at 20:03

greedybuddha

7,5073 gold badges38 silver badges50 bronze badges

Comments

Murali · Accepted Answer · 2013-06-04 20:18:32Z

0

Using random to select a random value from given values

 String randomLotteryWinner() 

{
   String []array={"person1","person2","person3","person4","person5"};

   String Winner=array[(int)(Math.random()*array.length)];

   return Winner;
}

answered Jun 4, 2013 at 20:18

Murali

7826 silver badges12 bronze badges

Collectives™ on Stack Overflow

Comparing array entries

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related