How to transform this program to arrays?

Question

import java.util.Random;

public class Hi {

    public static void main(String[] args) {
        Random random = new Random();
        int integer = random.nextInt(100 - 0) + 0;

        System.out.println(sumDigits(integer));
    }
    public static int sumDigits(int n) {

        int sumOfInteger = 0;
        while (n != 0) {
            sumOfInteger += n % 10;
            n /= 10;
        }
        return sumOfInteger;
    }
}

I need to use arrays instead of regular. This is what I have to do Program that generates 100 random integers between 0 and 9 and displays the count for each number. (Hint: Use an array of ten integers, say counts, to store the counts for the number of 0s, 1s, . . . , 9s.) I am getting single numbers but not the count. But at the same time I have to use arrays.

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

public class Hw7Problem3 {

    public static void main(String[] args) {

    System.out.println(sumDigits());

    }
    public static int[] sumDigits(int random) {

        int[] digits = new int[10];
        for (int i = 0; i < 100; i++){
          digits[(int) (Math.random() * 10)]++;
        }
        return digits;
    }
}

your question is unclear. you said *displays the count for each number* but you are summing them up — SweetWisher ツ, Nov 29 '14 at 07:26
Oh yes I need the count for each number, I am stuck on this, I have approach it in different ways but I don't get it. — Wilson, Nov 29 '14 at 07:29
I have to show 100 numbers that have 0 to 9 in each. Then I have to show what order is each number. Like number 5 will be in count 5 — Wilson, Nov 29 '14 at 07:33
http://stackoverflow.com/questions/25759408/frequency-distribution-of-words/25759613#25759613 — Vahid, Nov 29 '14 at 07:35

score 0 · Answer 1 · answered Nov 29 '14 at 07:34

0

I hope this will help you:

int counts[] = new int[10];
for(int i = 0; i < 100; i++) {
    int rnd = random.nextInt(10);
    counts[rnd] = counts[rnd] + 1;
}

so in counts[N] you can find how many times N was random generated.

answered Nov 29 '14 at 07:34

DontRelaX

744
4
10

score 0 · Accepted Answer · answered Nov 29 '14 at 07:40

Your assignment was to create 100 random integers between 0 and 10. So we need to start with an array of digits with which to count. We could use a Math.random() and multiply by 10 (to get a number from 0 to 9 inclusive) and increment that index in digits. Something like

int[] digits = new int[10];
for (int i = 0; i < 100; i++)
  digits[(int) (Math.random() * 10)]++;

Then you print it perhaps with

System.out.println(Arrays.toString(digits));

Across two runs I got

[11, 11, 9, 9, 6, 11, 9, 13, 11, 10]

and

[8, 6, 5, 11, 10, 9, 13, 10, 15, 13]

Which seem to suggest that it works.

@Wilson Yes, because that's my answer as a method but you forgot `Arrays.toString()` so you get the default toString from Object. `System.out.println(Arrays.toString(sumDigits()));` — Elliott Frisch, Nov 29 '14 at 07:51

How to transform this program to arrays?

2 Answers2