Sorting an array of objects by two doubles

Question

So I had a delimited file that I read into an array.

array[0] is the boxID (double)

and

array[1] is the movieID (double)

I have no clue how I'd be able to sort my array by these two doubles. Any comments? I've tried looking at other questions on this website but I just got confused by them. I'm currently in my first programming class.

Movies[] newMasterMovies = new Movies[200];

    int newMasterCount = 0;
    int masterCount = 0;
    int updateCount = 0;

    while (updateCount < updateTotalCounter || masterCount < masterTotalCounter) {

        String updateCompare = updateMovies[updateCount].getBoxID() + updateMovies[updateCount].getMovieID();
        String masterCompare = masterMovies[masterCount].getBoxID() + masterMovies[masterCount].getMovieID();
        int compare = updateCompare.compareTo(masterCompare);

        if (compare > 0) {
            newMasterMovies[newMasterCount] = masterMovies[masterCount];
            masterCount++;
            newMasterCount++;
        }

        if (updateMovies[updateCount].getActionCode() == "A") {
            newMasterMovies[newMasterCount] = updateMovies[updateCount];
            updateCount++;
            newMasterCount++;
        }

        if (updateMovies[updateCount].getActionCode() == "D") {
            updateCount++;
            masterCount++;
        }

        if (updateMovies[updateCount].getActionCode() == "C") {
            newMasterMovies[newMasterCount] = updateMovies[updateCount];
            updateCount++;
            newMasterCount++;
            masterCount++;
        }

    }

That is what my array looks like that I am trying to sort. I tried to do a selection sort but got confused since I want to sort by two properties, not just one.

Answer 1

This guy here does a wonders

  Arrays.sort(iArr);

Here is what it can do: Here is an example code

 public class ArrayDemo {

 public static void main(String[] args) {

     // initializing unsorted int array
     int iArr[] = {2, 1, 9, 6, 4};

     // let us print all the elements available in list
     for (int number : iArr) {
     System.out.println("Number = " + number);
     }

     // sorting array
     Arrays.sort(iArr);

     // let us print all the elements available in list
     System.out.println("The sorted int array is:");
     for (int number : iArr) {
     System.out.println("Number = " + number);
    }
  }
}

And the results should be like this

Number = 2

Number = 1

Number = 9

Number = 6

Number = 4

The sorted int array is:

Number = 1

Number = 2

Number = 4

Number = 6

Number = 9

Hopes this helps some

Answer 2

To simply sort your Movies[] you can use Arrays.sort and use a custom Comparator . Like this:

    Arrays.sort(masterMovies, new Comparator<Movies>() {
        @Override
        public int compare(Movies o1, Movies o2) {
            // compare boxID
            // compare movieID
            return 0; // return result
        }
    });

Arrays.sort use merge sort or binary insertion sort which are both more stable and faster than selection sort .

If you insist to do your selection sort, try to edit yor class Movies to implement Comparable interface, like this: class Movies implements Comparable<Movies> . And implement compareTo method like this:

    @Override
    public int compareTo(Movies o) {
        // compare boxID
        // compare movieID
        return 0; // return result
    }

And change your old compare code int compare = updateCompare.compareTo(masterCompare); to int compare=updateMovies[updateCount].compareTo(masterMovies[masterCount]); , then go on.