如何按Java中的第3列按升序对2D数组排序？

Question

我的代码旨在对员工列表进行排序，首先按部门（第一列）排序，然后按年龄（第三列）升序排序。 我搜索了几个小时都无济于事。 到目前为止，我的代码：

    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]);
        }
    }
}

我希望输出先按部门打印列表，然后再按年龄从小到大打印。 任何帮助表示赞赏。

Answer 1

您可以使用Arrays.sort并提供一个自定义比较器：

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]);
        }           
    });

实际上，更好的方法是创建自己的Employee类，并使其实现可比较的接口。

输出：

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

像这样

您的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;
    }
}

您的排序

 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]);
 }

输出

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