Question

I am stack for a while . I tried debugging but I couldn’t figure out the solution. I am trying to count the occurrence of numbers. So my problem is that when I print the output it is

3 occurs 1 times
1 occurs 1 times
0 occurs 1 times
2 occurs 1 times
1 occurs 2 times
3 occurs 2 times
2 occurs 2 times
0 occurs 2 times
10 occurs 1 times
4 occurs 1 times

instead of

1 occurs 2 times
0 occurs 2 times
2 occurs 2 times
3 occurs 2 time
10 occurs 1 times
4 occurs 1 times 

so if the number has more than 1 occurrence it should say it only once not as many times as there is occurrences. Cheers Here is the code

import java.util.*;

public class CountingOccuranceOfNumbers
{

    public static void main(String[] args) 
    {
        countNumbers();
    }

    public static void countNumbers()
    {
        Scanner input = new Scanner(System.in);
        Random generator = new Random();
        int[] list = new int[11];
        int[] counts = new int[150];
        int counter = 0;
        int number = 1;


        while(counter <= 10)
        {
                number = generator.nextInt(11);
                list[counter] = number;
                counter++;
        }   
        for(int i=0; i<list.length - 1; i++)
        {
            counts[list[i]]++;
//          System.out.print(list[i] + " ");

            System.out.println(list[i] +" occurs " +  counts[list[i]] + " times");
        }

    }

}

Answer 1

Another option is guava’s Multiset classes, which will track the count for you:

int values[] = ...;
Multiset<Integer> ms = HashMultiset.create();
ms.addAll(Ints.asList(list));

int count0 = ms.count(Integer.valueOf(0));
int count1 = ms.count(Integer.valueOf(1));

Here, Multiset, HashMultiset and Ints are all guava classes.

Note that Multiset does pretty much what someone mentioned above by using a Map and counter to track the counters. It’s just abstracted away from you to make your code simpler.