How do you sort a 2D array in ascending order by the 3rd column in java?

Question

My code is intended to sort a list of employees, first sorting by department (first column) and then sorting by age (third column) in ascending order. I have searched for hours to no avail. My code so far:

    public class Company
    {
    public static void main(String[] args)
    {
        String[][] departmentList = new String[13][3];
            departmentList[0][0] = "Accounting";
            departmentList[0][1] = "Counting Guru";
            departmentList[0][2] = "55";
            departmentList[1][0] = "Accounting";
            departmentList[1][1] = "Counting Pro";
            departmentList[1][2] = "45";
            departmentList[2][0] = "Accounting";
            departmentList[2][1] = "Counting Savvy";
            departmentList[2][2] = "40";
            departmentList[3][0] = "Accounting";
            departmentList[3][1] = "Counting Novice";
            departmentList[3][2] = "25";
            departmentList[4][0] = "Marketing";
            departmentList[4][1] = "Sales Guru";
            departmentList[4][2] = "50";
            departmentList[5][0] = "Marketing";
            departmentList[5][1] = "Sales Pro";
            departmentList[5][2] = "48";
            departmentList[6][0] = "Marketing";
            departmentList[6][1] = "Sales Savvy";
            departmentList[6][2] = "38";
            departmentList[7][0] = "Human Resources";
            departmentList[7][1] = "Hiring Guru";
            departmentList[7][2] = "58";
            departmentList[8][0] = "Human Resources";
            departmentList[8][1] = "Hiring Pro";
            departmentList[8][2] = "47";
            departmentList[9][0] = "Information Systems";
            departmentList[9][1] = "Hacking Pro";
            departmentList[9][2] = "46";
            departmentList[10][0] = "Information Systems";
            departmentList[10][1] = "Hacking Guru";
            departmentList[10][2] = "51";
            departmentList[11][0] = "Information Systems";
            departmentList[11][1] = "Hacking Savvy";
            departmentList[11][2] = "38";
            departmentList[12][0] = "Information Systems";
            departmentList[12][1] = "Hacking Novice";
            departmentList[12][2] = "23";

        for(int row = 0; row < departmentList.length; row++)
        {
            System.out.println(departmentList[row][0] + "\t" + departmentList[row][1] + "\t" + departmentList[row][2]);
        }
    }
}

I want the output to print the list according to department and then according to age, youngest to oldest. Any help is appreciated.

Answer 1

You can use Arrays.sort and provide a custom comparator :

Arrays.sort(departmentList, new Comparator<String[]>() {
        @Override
        public int compare(String[] o1, String[] o2) {
           int cmp =  o1[0].compareTo(o2[0]);
           return cmp != 0 ? cmp : o1[2].compareTo(o2[2]);
        }           
    });

Actually a better way would be to create your own Employee class and let it implement the comparable interface.

Output :

Accounting  Counting Novice 25
Accounting  Counting Savvy  40
Accounting  Counting Pro    45
Accounting  Counting Guru   55
Human Resources Hiring Pro  47
Human Resources Hiring Guru 58
Information Systems Hacking Novice  23
Information Systems Hacking Savvy   38
Information Systems Hacking Pro 46
Information Systems Hacking Guru    51
Marketing   Sales Savvy 38
Marketing   Sales Pro   48
Marketing   Sales Guru  50

Answer 2

Do like this

your Comparator

class SimpleComparator implements Comparator<String[]> {
    @Override
    public int compare(String[] o1, String o2[]) {       
        if(!o1[0].equalsIgnoreCase(o2[0])){
            return o1[0].compareToIgnoreCase(o2[0]);
        }
        int value1 = Integer.parseInt(o1[2]);
        int value2 = Integer.parseInt(o2[2]);
        if(value1!=value2){
            return new Integer(value1).compareTo(value2);
        }
        return 0;
    }
}

Your sorting

 Arrays.sort(departmentList,new SimpleComparator());
 for(int row = 0; row < departmentList.length; row++)
 {
      System.out.println(departmentList[row][0] + "\t" + departmentList[row][1] + "\t" + departmentList[row][2]);
 }

OutPut

Accounting  Counting Novice 25
Accounting  Counting Savvy  40
Accounting  Counting Pro    45
Accounting  Counting Guru   55
Human Resources Hiring Pro  47
Human Resources Hiring Guru 58
Information Systems Hacking Novice  23
Information Systems Hacking Savvy   38
Information Systems Hacking Pro 46
Information Systems Hacking Guru    51
Marketing   Sales Savvy 38
Marketing   Sales Pro   48
Marketing   Sales Guru  50