Question

Possible Duplicate:
java: How to split a 2d array into two 2d arrays

What is required is to split this array:

int[][] bitblock = {
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0},
    {1,0,1,0,1,0,1,0}};

This is an 8*8 array , I want to split it into left and right arrays and store them here:

int[][] leftblock = new int [bitblock.length][bitblock[0].length/2];
int[][] rightblock = new int [bitblock.length][bitblock[0].length/2];

I used the method Syste.arraycopy and I was able to split the bitblock to up and down arrays, I am kind of struggling to split it left and right:

System.arraycopy(bitblock, 0, leftblock, 0, leftblock.length);
System.arraycopy(bitblock, rightblock.length, rightblock, 0, rightblock.length)

Can someone please help ? Thanks

Answer 1

This should do the trick nicely:


int[][] bitblock = {{1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0},
{1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0}, {1, 0, 1, 0, 1, 0, 1, 0}};

    int[][] leftblock = new int[bitblock.length][bitblock[0].length / 2];
    int[][] rightblock = new int[bitblock.length][bitblock[0].length / 2];

    for (int i = 0; i < bitblock.length; i++) {
        for (int j = 0; j < bitblock[0].length / 2; j++) {
            leftblock[i][j] = bitblock[i][j];
        }

        for (int j = bitblock[0].length / 2; j < bitblock[0].length; j++) {
            rightblock[i][j - bitblock[0].length / 2] = bitblock[i][j];
        }
    }

You could also use System.arraycopy, as it makes the code more clear for future inspection.
As of performance, I don’t think it matters as long as your array is that small.