how to convert string abcdefghijklmnop to a 4x4 matrix in java?

Question

I am trying to convert a string to a matrix of 4x4 size. The matrix should contain the elements same as that of the string. For eg.

String="1234567890111213141516";

I need to convert this to a 4x4 matrix in java.

a[0][0]=1;
a[0][1]=2;

and so on. Can anyone suggest me the code for the same?

Answer 1

Here is a hint:

a[i][j] = Integer.valueOf(str.charAt(4 * i + j));

Figuring out how to use this to populate the entire matrix is left as an exercise for the reader.

PS This will work for a 16-character abcdefghijklmnop string as in your title; if the string is longer, as in the question, there is no unambiguous way to parse it into a 4x4 matrix.

PPS If all you need to do is set the elements to the consecutive numbers from 1 to 16, you don't need the string at all.

Answer 2

Indeed your question is an easy one, so I answer your question with some additional points that I think help you more than the answer itself:

First, this is the code:

int N = 4;
String delim = ",";
String s = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16";
String[] c = s.split(delim);
int[][] mat = new int[4][4];
int l = 0;
for (int i = 0; i < N; i++)
    for (int j = 0; j < N; j++,l++)
        mat[i][j] = Integer.valueOf(c[l]);

Notes:
Please
1 - don't a simple problem a real hard one!

if it's a hw you can convince the tutor about defining the string delimited with something like "," (if he/she insists) or whatever, and if this is a real project convince the customer, you don't want to torture yourself!

String s = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16";

2 - you said you want to split the string into a 4 x 4 matrix, what if you want a 5x5 matrix? So take advantage of constants, and the same for the delimiter

int N = 4;
String delim = ",";

Hope these help.

Answer 3

You should run two for loops through your string and fill up the matrix. (This can be done with one array too, but let's keep it simple.)

    String str ="1234567890111213141516";
    final int rowSize = 4;
    final int columnSize = 4;
    String[][] a = new String[rowSize][columnSize];
    // iterate
    for (int row = 0; row < rowSize; row++) {
        for (int column = 0; column < columnSize; column++) {
            a[row][column] = String.valueOf(str.charAt(rowSize * row + column));
        }
    }
    // test
    for (int row = 0; row < rowSize; row++) {
        for (int column = 0; column < columnSize; column++) {
            System.out.print(a[row][column] + " ");
        }
        System.out.println();
    }

Answer 4

For reading a String s = "1234567890abcdefghij" , you can add below code snippet :

char[][] a = new char[4][4];

for (int i = 0; i < 4; i++) {
    for (int j = 0; j < 4; j++) {
        a[i][j] = s.charAt(4 * i + j);
    }
}

this will help you. This will work for only one digit character only.