How to sort an array into columns

Question

I need help organizing an array in java. The code below prints out random numbers in a straight line. However, I want the code to print out four of those numbers and then continue on a new line. Essential, I want the code to print out four random numbers on the first line, then another 4 random numbers on the second, and so on and so forth.

import java.util.Arrays;
import java.util.Random;

public class SelectionSort{ 

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] array = new int[200];

        Random rand = new Random();

        // for acsending order
        for (int i = 0; i < array.length; i++) 



        array[i] = rand.nextInt(1000000) + 1;
        Arrays.sort(array);
        System.out.println(Arrays.toString(array));
        System.out.print("\n");


        // for descending order

        for (int i = array.length - 1; i >= 0; i--)
            System.out.print(array[i] + ", ");
    }

}

What do you want broken into 4-number lines: the ascending output, the descending output, or both? — Ted Hopp
– Ted Hopp, Commented Jul 5, 2018 at 3:26
StringBuilder, StringJoiner and/or String.format would be my recommendations — MadProgrammer
– MadProgrammer, Commented Jul 5, 2018 at 3:27
Please use curly braces around the for loop body, especially if you format the code like this. — Henry
– Henry, Commented Jul 5, 2018 at 3:29

MaTao · Accepted Answer · 2018-07-05 03:44:00Z

2

You need to print \n for each 4 numbers

import java.util.Arrays;
import java.util.Random;

public class SelectionSort { 

    public static void main(String[] args) {
        int[] array = new int[200];

        Random rand = new Random();

        // for acsending order
        for (int i = 0; i < array.length; i++) {

            array[i] = rand.nextInt(1000000) + 1;
        }

        Arrays.sort(array);
        System.out.println(Arrays.toString(array));
        System.out.print("\n");


        // for descending order

        for (int i = array.length - 1; i >= 0; i--) {
            System.out.print(array[i] + ", ");
            if (i % 4 == 0) { 
                // print \n for each 4 numbers.
                System.out.println("\n");
            }
        } 
    }
}

answered Jul 5, 2018 at 3:44

MaTao

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2 Comments

Sebastian Over a year ago

Thank you! but what if I also want the ascending output to be in four columns as well. Again, I appreciate the help!

Ted Hopp Over a year ago

@Sebastian - Use the same technique: an explicit loop with an index that you test. You can't use Arrays.toString(array) to do what you want.

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