How to fill a multidimensional array?
int[][] array = new int[4][6];
Arrays.fill(array, 0);
I tried it, but it doesn't work.
5 Answers
Here's a suggestion using a for-each:
for (int[] row : array)
Arrays.fill(row, 0);
You can verify that it works by doing
System.out.println(Arrays.deepToString(array));
A side note: Since you're creating the array, right before the fill, the fill is actually not needed (as long as you really want zeros in it). Java initializes all array-elements to their corresponding default values, and for int it is 0 :-)
2 Comments
Srikanth nadimpally
for instance variables java does(automatic initalization) but not for local variables So above the above code adds importance in some cases
aioobe
@JoelDeWitt, why? :)
Try this:
for(int i = 0; i < array.length; i++) {
Arrays.fill(array[i], 0);
}
I haven't tested it but I think it should work.
1 Comment
Argote
This is using fill for a regular int array only, hence the for loop.
Since array is really an array of arrays, perhaps you can try looping over each row and doing fill for each one individually.
Comments
First, note that 0 is the default value for int arrays, so you don't have to fill something with 0.
If you want your array to stay truly multidimensional, you'll need a loop.
public static void fill(int[][] array, int element) {
for(int[] subarray : array) {
Arrays.fill(subarray, element);
}
}
If you only need a 2D-array filled with the same element and don't want to change the subarrays later, you can use this trick:
public static int[][] create2DArray(int length, int subLength, int element) {
int[] subArray = new int[subLength];
Arrays.fill(subArray, element);
int[][] array = new int[length][];
Arrays.fill(array, subArray);
return array;
}
This works analogously for higher-dimensional arrays.
Comments
See this way:
Arrays.fill(array[0], 0);
Arrays.fill(array, array[0]);
1 Comment
trincot
This makes every sub-array, the exact same array, so that if you change
array[0][0], you also change array[1][0], array[2][0], ... to the same value. Not a good solution.
int index = (y * width) + x;-- you could even create a class that just exposes get/set methods that take x and y as separate arguments. Then you could fill the whole array without any looping.