I have a string containing the following:
String text = "abcdefghijkl"
I want to put it in a 2d array so there will be 4 rows of 3
this is currently what I have, its not working correctly though:
char boxChar[][] = new char[4][3];
int j,i;
for (i = 0; i<4; i++)
{
for (j=0; j<3; j++)
{
boxChar[i][j] = text.charAt((i+1)*(j));
}
}
return boxChar[row][col];
It looks like you got the indexes mixed up. I added some print statements to your original code with a modification to get the right char in your charAt instruction.
String text = "abcdefghijkl";
char boxChar[][] = new char[4][3];
int j,i;
for (i = 0; i<4; i++)
{
for (j=0; j<3; j++)
{
boxChar[i][j] = text.charAt(i*3+j);
System.out.print(boxChar[i][j]);
}
System.out.println();
}
Sometimes it can be helpful to jot it down on a piece of paper if it's not lining up how you expected.
With your input string, the positions on a 1d array are
a b c d e f g h i j k l
0 1 2 3 4 5 6 7 8 9 10 11
As you loop through to get the box array (matrix), your outer loop indicates that you want four rows and three columns, in other words
a b c
d e f
g h i
j k l
so for the first element, a, its position is (0,0), b is at (0,1) and so on. Your charAt(position) has to map the 2d positions to their corresponding 1d positions.
Just the wrong indexing, otherwise you're good:
String text = "abcdefghijkl";
int rows = 4;
int cols = 3;
char boxChar[][] = new char[rows][cols];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
boxChar[i][j] = text.charAt((i * cols) + j);
}
}
//return boxChar[row][col];
System.out.println(boxChar[0]);
System.out.println(boxChar[1]);
System.out.println(boxChar[2]);
System.out.println(boxChar[3]);
