Is there any way to fill two dimensional array with unique random number ? I tried so much but all of my tries are failed . I can do this
ArrayList<Integer> list = new ArrayList<>();
for (int i = 1; i < 26; i++) { //element will be in range (1,25)
list.add(i);
}
Collections.shuffle(list);
for (int j = 0; j < 5; j++) {
System.out.print(list.get(j) + " ");
}
System.out.println();
If you wanted to print a 5x5 matrix of numbers from the List, you just need two layers of for loops. See the below code in action here.
ArrayList<Integer> list = new ArrayList<>();
for (int i = 1; i < 26; i++) { // element will be in range (1,25)
list.add(i);
}
Collections.shuffle(list);
for (int j = 0; j < 5; j++) {
for (int k = 0; k < 5; k++) {
System.out.format("%3d ", list.get(j * 5 + k));
}
System.out.println();
}
System.out.println();
Example Output:
3 4 23 18 15
1 8 20 6 7
5 21 19 2 24
17 13 22 16 25
14 9 12 10 11
I guess you can use combination of library which generates the random number and hashset. Hashset to remember the random number generated so far, and if duplicate is generated, you re-generate until it gives you the unseen number
Try this.
static List<List<Integer>> uniqueRandomNumbers(int height, int width) {
List<Integer> list = IntStream.rangeClosed(1, height * width)
.boxed()
.collect(Collectors.toList());
Collections.shuffle(list);
List<List<Integer>> matrix = IntStream.range(0, height)
.mapToObj(i -> list.subList(i * width, (i + 1) * width))
.collect(Collectors.toList());
return matrix;
}
and
List<List<Integer>> matrix = uniqueRandomNumbers(5, 5);
for (List<Integer> list : matrix)
System.out.println(list);
result
[16, 4, 15, 14, 25]
[19, 11, 6, 21, 9]
[17, 20, 3, 1, 5]
[10, 7, 22, 18, 2]
[12, 13, 24, 23, 8]
Does this can help ?
public static void main(String[] args)
{
// declare arrays
int[][] ticketInfo;
String[][] seatingChart;
// create arrays
ticketInfo = new int [2][3];
seatingChart = new String [3][2];
// initialize the array elements
ticketInfo[0][0] = 15;
ticketInfo[0][1] = 10;
ticketInfo[0][2] = 15;
ticketInfo[1][0] = 25;
ticketInfo[1][1] = 20;
ticketInfo[1][2] = 25;
seatingChart[0][0] = "Jamal";
seatingChart[0][1] = "Maria";
seatingChart[1][0] = "Jacob";
seatingChart[1][1] = "Suzy";
seatingChart[2][0] = "Emma";
seatingChart[2][1] = "Luke";
// print the contents
System.out.println(ticketInfo);
System.out.println(seatingChart);
}
