I need a large series of arrays, right now I am creating them manually:
int[] row1 = new int[3];
int[] row2 = new int[3];
int[] row3 = new int[3];
I would like to create these in an array, something like this:
public final int SIZE = 3;
for (int i = 1;i <= 3;i++)
int[] row[i] = new int[3];
But I am not sure how to generate arrays in a loop.
How do I do this?
Specifically, how do I generate dynamic identifiers on each iteration?
Specifically, how do I generate dynamic identifiers on each iteration?
You don't. Instead, you realize that you've actually got a collection of arrays. For example, you could have:
int[][] rows = new int[3][3];
Or:
List<int[]> rows = new ArrayList<>();
for (int i = 0; i < 3; i++) {
rows.add(new int[3]);
}
Arrays always start at index 0, so for (int i = 1;i <= 3;i++) is wrong twice. Once for 1 and once for not using SIZE. You make a multidimensional array like,
public final int SIZE = 3;
int[][] tables = new int[SIZE][SIZE];
Note that every value in tables is 0. You could use Arrays.fill(int[],int) to give every element a single value,
Arrays.fill(tables, 1);
// [[1, 1, 1], [1, 1, 1], [1, 1, 1]]
Or, you might use a pair of for loops like
for (int i = 0; i < tables.length; i++) {
for (int j = 0; j < tables[i].length; j++) {
tables[i][j] = (tables[i].length * i) + j;
}
}
// [[0, 1, 2], [3, 4, 5], [6, 7, 8]]
And you can also use a literal assignment and you might use Arrays.deepToString(Object[]) to display your multi-dimensional arrays like,
int[][] tables = { { 8, 7, 6 }, { 5, 4, 3 }, { 2, 1, 0 } };
// [[8, 7, 6], [5, 4, 3], [2, 1, 0]]
System.out.println(Arrays.deepToString(tables));
Simply make it a 2D-array. Proceed as follows :-
public final int SIZE = 3;
int row[3][SIZE] = new int[3][SIZE];
Here you would use an array of arrays, a 2-dimensional array.
public final int SIZE = 3;
int[][] array = new int[SIZE][SIZE];
This way you don't need dymanic identifiers, you can just use an index. You can access one element like this:
// i is the index of the array, j is the index of the element
int element = array[i][j];
Based on asking specifically about arrays, you may not be interested in more bloated types. But if that's not an issue, you could use a Map. And put each array into the map with a unique identifier as the key.
Map myRows = new HashMap <String, int[]>();
myRows.put("row1", new int[] {1,2,3});
note: you could easily replace the String key with an Integer key.
