如何将6个整数的数组与2个整数的数组[19] [5]进行比较？

Question

I'm working on a project for school and can't figure this out. I'm a very beginning level beginner btw.

I have a 2d array called tickets[19][6] 20 tickets with 6 ints in each ticket. I'm trying to compare those 20 tickets to a regular array of ints with 6 numbers called winner[5] , which I read from a .txt file.

both arrays are stated as follows:

public static int[] winner = new int[5]
public static int[][] tickets = new int[19][5]

Please keep in mind I'm very new to this, and I appreciate any help in advance!

EDIT this is the loop I'm using to assign user input to my 2d array, just realized when I went through the whole thing that it was an endless loop. I thought writing code would be more....well, writing! Seems to be more like the art of debugging so far.

static void ticketNumberArray(){

    int number = 1;        // which of the six numbers you need from the ticket
    int ticketCount = 1;   // which ticket (out of 20) you are currently on

    while(ticketCount<21){ // sentinel controlled while loop,
                           // will continue until the twentieth ticket is entered
        System.out.println("Please type number " +number+ " of ticket number " +ticketCount+ ".");
                           //asks for the numbers of the ticket your currently on

        Scanner keyboard = new Scanner(System.in); // initiates a scanner variable

        int ticketNumber = keyboard.nextInt();     // assigns user input to the double variable ticketNumber
                                                   // and initializes as a double

        tickets[ticketCount-1][number-1]=ticketNumber;  // assigns user input into a 2-d array

        number++;           //Sentinel variable

        if(number==7){      //loop that controls the ticket count, every 6 numbers ='s one ticket
            ticketCount++;
            number=1;
        }
    }
}

Answer 1

First off, the number you put in the [ ] when you declare the array is the size of the array. So, to make an array with six items, you need to put [6] . The indexes will be numbered 0-->5.

You just need to loop over the ticket "rows" in the tickets array, and compare it to the winner array. Each row is an inviidual ticket. The "columns" in the 2D array would be the individual numbes that comprise the ticket.

You can use Louis's suggestion with Arrays.equal if the order of the individual numbers in the ticket matters. (ie. you can only win with ticket 0-1-2-3 if the winner is 0-1-2-3 -- most lotteries allow you to win any combination.)

for(int i=0; i < tickets.length; i++)
{
   int[] ticket = tickets[i];

   if(Arrays.equals(ticket, winner))
   {
      // This one is the winner

      // For efficiency you should probably stop looping
      break;
   }
}

---

Edit:

A lot of intro professors don't like it when students use the API. So, you'd have to write you own equals function.

private static boolean areEqual(int[] a, int[] b)
{ 
   if(a == null && b == null)
       return true;

   // Not equal if one is null and the other is not     
   if(a == null || b == null)
       return false;

   if(a.length != b.length)
       return false;

   // When we get here we have to check each element, one by one
   // Implementation left as exercise :-)
}

Answer 2

Do the tickets have 5 integers, or 6? Your question contradicts itself.

In any event, if you just want to check if the integers in the tickets match -- if they have exactly the same values in exactly the same order -- the simplest solution is just to use Arrays.equals(int[], int[]) .