array sort multidimensional array to match second array

Question

I have a single demenational array with student names and a 2D array with student marks, I can sort the names fine but I cannot get the marks to match (as they have to stay in the same order). Here is my attempted code:

static String[] studentNamesArray = new String[10];
static int[][] studentMarksArray = new int[10][3];

  static void sortAlphabetical() { 
    String tempName;
    int intSwap;
    boolean flag = false;
    while (flag==false) {
      flag = true;
      for (int i = 0; i < 9; i++) {
        if (studentNamesArray[i].compareTo(studentNamesArray[i + 1])>0) {
          tempName = studentNamesArray[i];
          studentNamesArray[i] = studentNamesArray[i + 1];
          studentNamesArray[i + 1] = tempName;

          for(int y=0;y<2;y++){
          intSwap = studentMarksArray[i][0];
          studentMarksArray[i][y] = studentMarksArray[i+1][y+1];
          studentMarksArray[i+1][y+1] = intSwap;
          }
          flag = false;
        }
      }
    }
  }

Any reasons that you don't want to create a Student object holding its name and its marks, then create a Student[] array and sort it by name using a Comparator ? — Alexis C.
– Alexis C., Commented Nov 28, 2013 at 15:58

Alexis C. · Accepted Answer · 2013-11-28 16:12:32Z

3

You just have to swap the marks arrays like you did for the names :

static void sortAlphabetical() { 
        String tempName;
        int [] intSwap; //<-- note I changed this as an int[] array
        boolean flag = false;
        while (flag==false) {
          flag = true;
          for (int i = 0; i < studentNamesArray.length-1; i++) { //<-- note I changed this to length - 1 to avoid IndexOutOfBoundsException
            if (studentNamesArray[i].compareTo(studentNamesArray[i + 1])>0) {
              tempName = studentNamesArray[i];
              studentNamesArray[i] = studentNamesArray[i + 1];
              studentNamesArray[i + 1] = tempName;

              intSwap = studentMarksArray[i];
              studentMarksArray[i] = studentMarksArray[i+1];
              studentMarksArray[i+1]= intSwap;
              flag = false;
            }
          }
        }
      }

    static String[] studentNamesArray = new String[3];
    static int[][] studentMarksArray = new int[3][3];

    public static void main (String[] args) throws java.lang.Exception {
        studentNamesArray[0] = "Mark";
        studentNamesArray[1] = "Anna";
        studentNamesArray[2] = "Arnold";

        studentMarksArray[0] = new int[]{1,2,3};
        studentMarksArray[1] = new int[]{4,5,6};
        studentMarksArray[2] = new int[]{0,0,0};

        sortAlphabetical();
        System.out.println(Arrays.toString(studentNamesArray));
        System.out.println(Arrays.deepToString(studentMarksArray));

    }

Output :

[Anna, Arnold, Mark]
[[4, 5, 6], [0, 0, 0], [1, 2, 3]]

edited Nov 28, 2013 at 16:12

answered Nov 28, 2013 at 16:05

Alexis C.

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3 Comments

Colin747 Over a year ago

Can you explain why you changed intSwap to an array?

Alexis C. Over a year ago

@Colin747 Because initially each mark array is associated as the same index position as the String array right ? So if you swap two names in the array, you have too swap their corresponding mark arrays too.

Colin747 Over a year ago

I wasn't questioning why you did it, I just wanted to make sure I understood correctly what was going on, your solution worked great, thanks

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