Matrix [source code]

public class Matrix {
    public static String printMatrix (int[][] matrix) {
        StringBuilder sb = new StringBuilder("{==================\n");
        for (int[] column : matrix) {
            for (int num : column) {
                sb.append(num + "\t");
            }
            sb.append("\n");
        }
        sb.append("==================}\n");
        return sb.toString();
    }

    public static int[][] transpose(int[][] grid) {
        int m = grid.length, n = grid[0].length;
        int[][] res = new int[n][m];
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                res[j][i] = grid[i][j];
            }
        }
        return res;
    }

    public static String printMatrix (char[][] matrix) {
        StringBuilder sb = new StringBuilder("{==================\n");
        for (char[] column : matrix) {
            for (char num : column) {
                sb.append(num + "\t");
            }
            sb.append("\n");
        }
        sb.append("==================}\n");
        return sb.toString();
    }

    public static String printMatrix (double[][] matrix) {
        StringBuilder sb = new StringBuilder("{==================\n");
        for (double[] column : matrix) {
            for (double num : column) {
                sb.append(num + "\t");
            }
            sb.append("\n");
        }
        sb.append("==================}\n");
        return sb.toString();
    }

    public static String printMatrix (boolean[][] matrix) {
        StringBuilder sb = new StringBuilder("{==================\n");
        for (boolean[] column : matrix)
            sb.append(Printer.array(column) + "\n");
        sb.append("==================}\n");
        return sb.toString();
    }    

    public static char[][] buildFromString(String[] ar) {
        int m = ar.length;
        char[][] res = new char[m][];
        for (int i = 0; i < m; i++)
            res[i] = ar[i].toCharArray();
        return res;
    }

    public static int[][] listToMatrix(List<List<Integer>> lss) {
        int[][] res = new int[lss.size()][];
        for (int i = 0; i < res.length; i++) {
            List<Integer> ls = lss.get(i);
            res[i] = new int[ls.size()]; //do not forget
            for (int j = 0; j < ls.size(); j++)
                res[i][j] = ls.get(j);
        }
        return res;
    }

    public static String printMatrix (Object[][] matrix) {
        StringBuilder sb = new StringBuilder("{==================\n");
        for (Object[] column : matrix) {
            for (Object num : column) {
                sb.append(num + "\t");
            }
            sb.append("\n");
        }
        sb.append("==================}\n");
        return sb.toString();
    }    
}