为什么我在ArrayList中而不是整数值中得到此结果？

Question

Hello and Thanks for all your peoples help.

I am making a concentration game as a learning project. I was having some problems with the random generator working right which was solved by Jeeter in this thread. Jeeter's Solution

and this is the code which I am using to get the numbers and store them into an ArrayList

ArrayList<int[]> al = new ArrayList<int[]>();

int offsetX = 130;
int offsetY = 100;

switch(Game.difficulity){
case EASY:
    GameConstants.cardsToDraw = 6;
    //generate cards
    UniqueRandoms randpEA = new UniqueRandoms(GameConstants.cardsToDraw);
    int[] cardsEA = new int[GameConstants.cardsToDraw];
    System.out.print("The Picks are: "); //Testing purposes only.

    for (int i = 0; i < GameConstants.cardsToDraw; i++) {
       cardsEA[i] = randpEA.nextInt();  // grabs the results so they can be manulipated
       al.add(cardsEA);                 // add the results to an ArrayList
       System.out.print(cardsEA[i] + ", "); //testing to see what is chosen

       // this line just shows the result as cards onscreen.        
       handler.addcard(new GameCard((offsetX) + i*90, (GameConstants.CENTER_Y - offsetY), cardsEA[i], res));
                        }
      //end of generate cards
      System.out.print("\n");
      System.out.println("Contents of al: " + al);
      Game.state = GameState.EASY_GAME;
      break;

This is the easy code block to keep this post short.

the results are this when I run the program:
Cards to draw: 6
The Picks are: 5, 2, 4, 1, 3, 6,
Contents of al: [[I@44d74990, [I@44d74990, [I@44d74990, [I@44d74990, [I@44d74990, [I@44d74990]

What my question is why am I getting the crazy numbers instead of the actual integers and how can I fix this?

Because I have to do the following:

1. Store the results
2. Duplicate the results
3. Shuffle the ArrayList
4. retrieve the values when I need to use them

So far I am trying to store the results and it does not look like it doing what I expect and then I have to figure out how to duplicate the results in the ArrayList.

My GitHub Project: Here

Answer 1

You need to manually loop through the ArrayList and then through each array in the list to print each value. What you need to do is:

 System.out.print("Contents of al: ");
 for(int[] ia: al){ 
    for(int i: ia)
       System.out.print(i + ", ");
 }
 System.out.println();

What it doing now is printing the reference of each array in the list.

Answer 2

try printing al.toString() instead of al

al.toString() will format its contents to a readable form.

EDIT: but if al contains int[] follow the answer posted by Thomas

Answer 3

Facts: 1) ArrayList cannot store primitives, hence your integers are stored as Integer wrappers

2) the crazy numbers are memory references of the respective Integer objects, and for some reason the toString() implementation of that object return the memory locations

hence you have to loop the ArrayList and use get() to get the values

edit:

just noticed

cardsEA[i] = randpEA.nextInt();  // grabs the results so they can be manulipated
  al.add(cardsEA);

you need to change it as

cardsEA[i] = randpEA.nextInt();  // grabs the results so they can be manulipated
  al.add(cardsEA[i]);

to get the desired result

Answer 4

By this little snippet:

for (int i = 0; i < GameConstants.cardsToDraw; i++) {
   cardsEA[i] = randpEA.nextInt();
   al.add(cardsEA);

It seems like what you are wanting to do is not have an ArrayList<int[]> because what you have now is an ArrayList of arrays. By doing al.add(cardsEA); on each iteration you are just adding the same array to the list repeatedly. When you try to print the list you are getting the memory address of the array for each time you added it in the loop. It seems like this what you are wanting:

ArrayList<Integer> al = new ArrayList<Integer>(0);

Then change the line in the loop to this:

al.add(cardsEA[i]);

Though if this is the case you don't need to create the array at all. You can change your loop to this:

for (int i = 0, card; i < GameConstants.cardsToDraw; i++) {
   card = randpEA.nextInt();
   al.add(card);
   System.out.print(card + ", ");

   handler.addcard(new GameCard((offsetX) + i*90, (GameConstants.CENTER_Y - offsetY), card, res));

Alternatively if you want both the array and the list something you can do is this:

Integer[] cardsEA = new Integer[GameConstants.cardsToDraw];

Then don't bother working with the list until after the loop and do either this:

// declaration
List<Integer> al;

// after the loop
al = Arrays.asList(cardsEA);

Or if you need ArrayList reference instead of List do this:

// declaration
ArrayList<Integer> al;

// after the loop
al = new ArrayList<Integer>(Arrays.asList(cardsEA));

Or:

// declaration
ArrayList<Integer> al = new ArrayList<Integer>();

// after the loop
al.addAll(Arrays.asList(cardsEA));

Lots of ways to make a list from an array. If you want to create the list as starting as empty, if possible instantiate it as new ArrayList<Integer>(GameConstants.cardsToDraw) because then the ArrayList will potentially not need to be internally resized.