Merge sorting an array then adding

Question

I finally got my program to sort my array but I cannot get it to add it. I am getting an error that reads:

MergeSorter.java:21: error: non-static method sumOfArray(int[],int) cannot be referenced from a static context

Code:

import java.util.Arrays;

public class MergeSorter{ 
   public static void sort(int[] a)
   {  
      if (a.length <= 1) { return; }
      int[] first = new int[a.length / 2];
      int[] second = new int[a.length - first.length];
      for (int i = 0; i < first.length; i++) 
      { 
         first[i] = a[i]; 
      }
      for (int i = 0; i < second.length; i++) 
      { 
         second[i] = a[first.length + i]; 
      }
      sort(first);
      sort(second);
      merge(first, second, a);
      int sum =sumOfArray(a, a.length-1); 
   }

 private static void merge(int[] first, int[] second, int[] a){         
     int iFirst = 0; 
      int iSecond = 0;
      int j = 0; 
      while (iFirst < first.length && iSecond < second.length){  
         if (first[iFirst] < second[iSecond]) {  
            a[j] = first[iFirst];
            iFirst++;
         }
         else{  
            a[j] = second[iSecond];
            iSecond++;
         }
         j++;
      }
      while (iFirst < first.length){ 
         a[j] = first[iFirst]; 
         iFirst++; j++;
      }
      while (iSecond < second.length){ 
         a[j] = second[iSecond]; 
         iSecond++; j++;
      }
   }

   public int sumOfArray(int[] a, int n){
    if (n == 0)
        return a[n];
    else
        return a[n] + sumOfArray(a, n-1);
   }
}

Thanks guys! I feel so dumb! I have been staring at this all night! — JBoom, Apr 08 '15 at 13:14

score 0 · Accepted Answer · answered Apr 08 '15 at 12:57

0

Make it static? like :

public static int sumOfArray(int[] a, int n)
{
    if (n == 0)
        return a[n];
    else
        return a[n] + sumOfArray(a, n-1);
}

answered Apr 08 '15 at 12:57

Bhavesh sethi

24
4

score 0 · Answer 2 · edited May 23 '17 at 12:17

0

See this post: Non-static variable cannot be referenced from a static context

In short, you need to make the method static, or call it on an instance of the class.

edited May 23 '17 at 12:17

Community

1
1

answered Apr 08 '15 at 13:00

Ben Kern

26
2

score 0 · Answer 3 · answered Apr 08 '15 at 13:01

An easy fix would be to change

 public int sumOfArray(int[] a, int n)

to

 public static int sumOfArray(int[] a, int n)

otherwise you would have to create a MergeSorter object and call the sumOfArray method:

 int sum =new MergeSorter().sumOfArray(a, a.length-1)

Merge sorting an array then adding

3 Answers3