The previous reply might be
misleading, so I bother everyone with my reply to all.
Since Java is similar to C/C++ in many ways, unlike Fortan,
two--dimensional arrays are arranged in row-major not column-major in
Java.
This means that the 1st index refers to a row, not a column and the 2nd
index refers to a column, not row.
This means that the following declaration:
int[][] a = new int[3][4];
and the following initialization:
a[0][0] = 1;
a[0][1] = 2;
a[0][2] = 3;
a[0][3] = 4;
a[1][0] = 5;
a[1][1] = 6;
a[1][2] = 7;
a[1][3] = 8;
a[2][0] = 9;
a[2][1] = 10;
a[2][2] = 11;
a[2][3] = 12;
produces:
[[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]]
Also, row-major arrangement dictates that traversing the array in the
following manner achieves maximum cash efficiency:
public class MultiDimensionalArrayExample {
public static void main(String[] args) {
int a[][] = new int[][]{{1,2,3,4}, {5,6,7,8}, {9,10,11,12}};
for(int i = 0; i < 4; i++) {
for(int j = 0; j < 3; j++) {
System.out.println(a[i][j]);
}
}
}
}
Shawn Ayromloo
Néstor wrote:
The 1st part in a multidimensional array indicates the column
(vertical) position
The 2nd part in a multidimensional array indicates the row
(horizontal) position
The 3rd part in a multidimensional array is the depth position
Array[4]x[3]:
[][][][]
[][][][]
[][][][5]
The value '5' is in position [2][3]
Array[4]x[3]x[3]:
[] [] []/ [][][][]
[5][][]/ [][][][]
The slash is used to indicate the depth or 3rd dimension of the
array
The value '5' is in position [1][0][2]
I hope this helps :-)
On Sun, Feb 22, 2009 at 9:16 AM, <[email protected]>
wrote:
Franz:
I will answer as many questions as I can:
1. The memory required for a 4x3 array of int would be 4 bytes per
integer x 4 x 3 = 48 bytes total.
2. The easiest way to fill a 3D array like that would probably be with
nested-for loops. i.e.:
for (int i = 0; i < 50; i++) {
for (int j = 0; j < 128; j++) {
for (int k = 0; k < 256; k++) {
num[i][j][k] = ...
}
}
}
3. I can't think of an easy way to explain this one. A two-dimensional
array is an "array of arrays" (for example, from question #1, an array
of 4 arrays of 3 int's). A 3D array is an expansion from that (an array
of arrays of arrays). Sorry, I can't think of another way to say that.
4. I prefer to think of that situation as 50 rows, 128 columns and 256
"layers". If you think of a box sitting on the floor, the length of the
box would be, for example, the rows (say 50), the width of the box
would be the columns (128), and the third number would be how far off
of the floor (256). Don't know if that helps or not, but that's how I
picture it.
5. How much memory is consumed would depend on the values that you are
storing in the array. It would be (50x128x256) x the size of the type
of data you're storing (4 for int, 1 for boolean, etc.).
6. I can't help you on this one. I haven't gotten up to GUI or AWT yet.
Cheers!
Eric
On Feb 22, 2009 7:34am, franzgabriel < [email protected]>
wrote:
>
>
> Somebody help me please, I still struggling to understand array
multi
>
> Dimension,
>
> My question is :
>
>
>
> 1. if I create 2 dimensional array 4 x 3 and the data type integer
in
>
> 32 bit computer how much memory will consume? Is it still only 4
byte
>
> or become doubler ??
>
>
>
> 2. how to fill values in row & column after initialized fixed
>
> dimension size in 3 D array:
>
>
>
> int [ ][ ][ ] num;
>
> num = new int [50][128][256];
>
>
>
> 3. What does it means 50 x 128 x 256 in array 3 D?
>
>
>
> 4. in array 3D 50 is become Row, 128 is column, and the 256 is
column,
>
> Is it right?
>
>
>
> 5. from above no.3 question the total is 1.651.200 field to store
data
>
> value, How much a memory will consume?
>
>
>
> 6. What does array use for in our java programming actually in GUI
>
> (AWT)?? only store a value or any different purpose?
>
>
>
>
>
>
>
>
>
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