Sort matrix by columns&rows

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Main {

    void swapChars(char[] s, int i, int j) {
        char tmp = s[i];
        s[i] = s[j];
        s[j] = tmp;
    }

    abstract class ISwapper {
        abstract void swap(char [][] matrix, int i, int j);
    };

    class SwapperColumns extends ISwapper {
        void swap(char [][] matrix, int i, int j) {
            int rowsCount = matrix.length;
            for (int k = 0; k < rowsCount; ++k) {
                swapChars(matrix[k], i, j);
            }
        }
    };

    class SwapperRows extends ISwapper {
        void swap(char [][] matrix, int i, int j) {
            char[] tmp = matrix[i];
            matrix[i] = matrix[j];
            matrix[j] = tmp;
        }
    };

    void Sort(char [][] matrix, char [] keys, ISwapper swaper) {
        int size = keys.length;
        for (int i = 0; i < size; ++i) {
            for (int j = i + 1; j < size; ++j) {
                if (keys[i] > keys[j]) {
                    swapChars(keys, i, j);
                    swaper.swap(matrix, i, j);
                }
            }
        }
    }

    void show(char[][] matrix) {
        System.out.println("Matrix:");
        for (int i = 0, k = 0; i < matrix.length; ++i) {
            for (int j = 0; j < matrix[0].length; ++j) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }

    void run() {
        char[] keysRows = "dcba".toCharArray();
        char[] keysColumns = "dcba".toCharArray();
        char[][] matrix = new char[keysRows.length][keysColumns.length];
        // init matrix
        for (int i = 0, k = 0; i < matrix.length; ++i) {
            for (int j = 0; j < matrix[0].length; ++j) {
                matrix[i][j] = (char)(97 + k++);
            }
        }
        show(matrix);
        // sort solumns
        Sort(matrix, keysColumns, new SwapperColumns());
        show(matrix);

        // sort rows
        Sort(matrix, keysRows, new SwapperRows());
        show(matrix);
    }

    public static void main(String []args) {
        (new Main()).run();
    }
}