Java- Moving elements from a ArrayList to an Array

Question

I currently have a randomly mixed ArrayList.

public static void main(String[] args) {
    ArrayList<Integer> solution = new ArrayList<>();
    for (int i = 1; i <= 48; i++) {
        solution.add(i);
    }
    Collections.shuffle(solution);

This gives me a ArrayList with the numbers 1-48 randomly mixed. Now I have 4 arrays and I want to randomly add the elements of the ArrayList with out repetition.

 int[] heartsRow = new int[14];
 int[] diamondsRow = new int[14];
 int[] spadesRow = new int[14];
 int[] clubsRow = new int[14];

The reason the new arrays contain 14 elements is because the first two elements will always be the same.

    heartsRow[0] = 1;
    heartsRow[1] = 0;
    diamondsRow[0] = 14;
    diamondsRow[1] = 0;
    spadesRow[0] = 27;
    spadesRow[1] =0;
    clubsRow[0] = 40;
    clubsRow[1] = 0;

I want to completely fill each array with non-repeating elements of the ArrayList.

0ddlyoko · Accepted Answer · 2017-10-07 12:45:17Z

1

You can make 4 for loops, from 0 to 11, 12 to 23, 24 to 35 and 36 to 47, and add in your lists.

for (int i = 0; i < 12; i++)
    heartsRow[i + 2] = solution.get(i);

for (int i = 0; i < 12; i++)
    diamondsRow[i + 2] = solution.get(i + 12);

for (int i = 0; i < 12; i++)
    spadesRow[i + 2] = solution.get(i + 24);

for (int i = 0; i < 12; i++)
    clubsRow[i + 2] = solution.get(i + 36);

answered Oct 7, 2017 at 12:45

0ddlyoko

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janos · Accepted Answer · 2017-10-07 12:50:23Z

1

You could use a counting loop over the list, increment the counter by 4 in each step, and assign elements to the arrays with adjusted offsets:

for (int i = 0; i + 3 < solution.size(); i += 4) {
  int j = i / 4;
  heartsRow[2 + j] = solution.get(i);
  diamondsRow[2 + j] = solution.get(i + 1);
  spadesRow[2 + j] = solution.get(i + 2);
  clubsRow[2 + j] = solution.get(i + 3);
}

answered Oct 7, 2017 at 12:50

janos

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