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My homework is to create a QRcode generator and I am stuck at creating the two Timing Pattern of the QR code base matrix. scheme of a QR code So I am looking for a way to create a checkboard using a 2D array, then use only the first and the first column to fill two other array with successively a black dot, a white dot, a black dot and so on. Then I fill the horizontal Timing Pattern Array with the first row and the vertical Timing Pattern with the first column. For this I use two methods: 1)Creation the checkboard and "filling" of the Timing Pattern, and 2)Declaration of the two TimingPatern arrays and then fill them

This is the code I have created :

//method to create the checkboard
public static int[][] timingPatternFilling (int[][] timingPattern) {
    for (int i=0;i<timingPattern[0].length-1;i++)
        for (int j=0;j<=timingPattern[1].length-1;j++) 
            if (((i%2==0)&&(j%2==0))||((i%2==1)&&(j%2==1))) { 
                timingPattern[i][j] = B;
                System.out.print(timingPattern[i][j]);
            } 
            else {
                timingPattern[i][j] = W;
                System.out.print(timingPattern[i][j]);
            }
        System.out.println();
    return timingPattern;
}
//method to create the Timing Pattern 
public static void addTimingPatterns(int[][] matrix) {
    // creation of the Timing Pattern (The calculation "matrix[1].length-2*(finderPatternSize+1)" allow to calculate the timingPattern length depending on the size of the matrix minus 2 times the size of the finder Pattern size
    int timingPatternVertical[][] = new int [matrix[0].length-(2*whiteSquareSize)][timingPatternLength];
    int timingPatternHorizontal[][] = new int [timingPatternLength][matrix[1].length-(2*whiteSquareSize)];
    //filling with the Black Pattern
    timingPatternFilling(timingPatternVertical);
    timingPatternFilling(timingPatternHorizontal);

So when I tried to run ths code I get the following error message : java.lang.ArrayIndexOutOfBoundsException. I think this related to the length of the arrays.

How can I solve this?

Sebastian Kaczmarek
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John Faraday
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  • it's indeed related to the length of the array. It means you are trying to get to an index which is the same as the size of the array or greater, which do not exist (or a negative id) – Stultuske Oct 28 '19 at 07:18

1 Answers1

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Your for loops look weird. Try something like this:

for (int i=0;i<timingPattern.length;i++)
    for (int j=0;j<=timingPattern[i].length;j++)
Maurice Perry
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