2D Array from user column number input

Question

I'm trying to make a 2D array using the following:

• User selects a number of random numbers to be included in array
• User selects a number of columns to place those numbers in for the 2D array

The output looks as follows:

230 234 240 245 311

334 396 398 402 415

415 415 425 445 450

450 451 462 467 488

496 513 516 521 534

548 553 560 566 567

570 571 575 579 579

591 597 611 618 620

629 630 638 648 662

where the user in this case would have entered 5 as the number of columns. They can choose any number up to a specific number! This means I can not just enter 5 as the column number, but it must be based off their input. Snippets of my code are shown here (pulled out of different packages/classes, but the only applicable code for this specific problem):

public class NumberGenerator {
    private ArrayList<Integer> numbers;
    private Random randomGenerator;

System.out.print("\nEnter the number of numbers (maximum 5000) you would like: ");
        input = this.scan.nextLine();
        int userOption = Integer.parseInt(input);
        while (userOption > 5000 || userOption < 1) {
            System.out.print("Enter the number of numbers (maximum 5000) you would like: ");
            input = this.scan.nextLine();
            userOption = Integer.parseInt(input);
        } this.userNumber.generateNumbers(userOption);

System.out.print("\nEnter the number of numbers per line (maximum 12): ");
        input2 = this.scan.nextLine();
        int userOption2 = Integer.parseInt(input2);
        while (userOption2 > 12 || userOption2 < 1) {
            System.out.print("Enter the number of numbers per line (maximum 12): ");
            input2 = this.scan.nextLine();
            userOption2 = Integer.parseInt(input2);
        } this.userColumns = (userOption2);

The rest of my coding and solutions are tested and running, so I know these are working snippets of code. Just need some help figuring out how to code a new method to call the 2D array as shown for formatting. Any help would be greatly appreciated.

Answer 1

I am assuming you generated the required list of numbers and you have the required column size. Then you can print the out put using the following method:

static void format(List<Integer> numberList,int columnSize){

        int totalLength = numberList.size();
        int index=0;
        for(; (index+columnSize) <= totalLength ;index+=columnSize ){
            System.out.println(String.format(getRowFormat(columnSize), numberList.subList(index, index+columnSize).toArray()));
            //or use this
            //System.out.printf(rowFormat.toString()+"\n", numberList.subList(i, i+columnSize).toArray());
        }
        if(index <= totalLength){//to handle pending values if any.
            System.out.println(String.format(getRowFormat(totalLength - index), numberList.subList(index, totalLength).toArray()));
        }
    }
    //handling format
    private static String getRowFormat(int columnSize) {
        StringBuilder rowFormat = new StringBuilder();
        for(int j=0;j<columnSize;j++){
            rowFormat.append("%10d");
        }
        return rowFormat.toString();
    }

call this from your code as:

format(numbers,this.userColumns);