How to sort multiple arrays of different types (int and String)

Question

So I read from a text file, line by line, some information and I basicly save it in memory to arrays of different types (string and int). In total I have 2 arrays of String and 6 of int.

I want to sort 1 of the arrays (String) alphabetically and based on that sort the other arrays of string and ints in positions that were saved.

Text file example: B,United States,3,1,0,2,2,7

C,United Kingdom,3,1,2,0,2,1

A,Denmark,3,3,2,0,2,1

Those arrays that I mention are saved whenever I read one line in the text file. So, I have a string,string,int,int,int,int,int in the position 0 for starters and so on until the last line is read.

Ps: After I read the text file I'm not supposed to have again the text file and only work with the information saved in memory. (not working with objects)

Answer 1

Create a single Object which represents a combination of the data types that you have for a single 'entry', and make it implement Comparable for that type.

public class MyEntry implements Comparable<MyEntry> {
     private String theStringToSortOn;

     private String theOtherString;
     private int theFirstInt;
     private int theSecondInt;
     // ...

     public int compareTo(final MyEntry entry) {
          int comparison = String.compare(this.theStringToSortOn, entry.theStringToSortOn);
          if (comparison != 0) {
              return comparison;
          }
          // Do some other rudimentary sorting based on the other fields of the class.
     }
}

Then all you need to do is add these to a List and sort it.

---

If you're intent on sticking with the array based implementation however, then you'll need to give some form of way to identify which indices have changed in the array that you sort (and what they changed from and to), and then mirror those changes to the other arrays.

Without writing code for you, here's a naive implementation of how to achieve this with just arrays:

• Take a copy before you sort the array so you can track where indices moved to.
• Create another array of int s, of the same length as this array.
• Sort the array.
• Iterate over the original, and for each element iterate over the sorted one to find the new index.
• Store this new index in your array of int s (in the position which denotes the unmodified index).
• Use this 'sorting/index array' to change the indices of all of the other arrays that you need to sort according to the first one.