Sorting multidimensional arrays

Question

int [][] div = {
                 {1, 1, 2},
                 {2, 1, 2},
                 {1, 2, 2},
                 {3, 1, 2},
                 {1, 2, 3},
                 {2, 1, 1},
                 {1, 1, 1}
               };

I want to sort this array according to the first column.

I've done something but I messed up. I really don't know how to swap the other columns together with the first column.

for(int x = 0; x < div.length-1; x++) {
  for(int y = 0; y < div.length-1;y++) {
    if(div[y][0] > div[y+1][0]) {
      tmp = div[y][0];
      div[y][0] = div[y+1][0];
      div[y+1][0] = tmp;
    }                   
  }
}
for(int x = 0; x < arr.length; x++) {   
  System.out.print(div[x][0]+" \t" + div[x][1] + "\t"+ div[x][2] +  "\n");          
}

vlatkozelka · Accepted Answer · 2015-12-04 18:06:14Z

4

You were close but messed up the swap, tmp=div[y][0] is an integer, but you want to swap an array.

Consider div[][] to be an array of arrays, if you want to swap an array inside of it with another, you need a tmp value that is an array not just an int so :

int[] tmp;    

    for (int x = 0; x < div.length - 1; x++) {

                if (div[x][0] > div[x + 1][0]) {
                    tmp = div[x];
                    div[x] = div[x + 1];
                    div[x + 1] = tmp;

                }

            }

To print the array:

 for(int x = 0; x < div.length; x++)
 {   
     for(int y = 0; y < div[x].length;y++)
        {
           System.out.print(div[x][y]+" ");
        }
     System.out.println();    


  }

edited Dec 4, 2015 at 18:06

answered Dec 4, 2015 at 17:46

vlatkozelka

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5 Comments

Eric G Over a year ago

tmp should be int [] tmp its being set to an array of int not a 2d array of ints

Jacob Hernandez Over a year ago

so what would i print, tmp or the array div?

vlatkozelka Over a year ago

Printing depends on the format you want, just access the values inside div[][] like you did while sorting and print them. tmp is just a temporary value you use for the swap

Jacob Hernandez Over a year ago

what if i want to print the whole sorted array?

vlatkozelka Over a year ago

@noviceJ sorry my answer was wrong, tried it now to make sure , should work.

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