2D matrix questions

// only valid for square matrix
    public int[][] transpose(int[][] matrix) {
        int n = matrix.length;

        int curr_r = 0;
        int curr_c = 0;

        while(curr_r<n){
            int i = curr_r;

            for(int j = curr_c; j<n; j++){
                // swap row, col wit
                int temp = matrix[i][j];

                matrix[i][j] = matrix[j][i];
                matrix[j][i] = temp;
            }
            curr_r++;
            curr_c++;
        }

        return matrix;
    }

    public static void printSpiral(int[][] matrix){
        int n = matrix.length;
        int m = matrix[0].length;

        int sr = 0, sc = 0, er = n-1, ec = m-1;
        int row,col;

        while(sr<=er && sc<=ec){
            // print starting col from sr to er
            col = sc;
            for(row=sr; row<=er && sc<=ec; row++){
                System.out.print(matrix[row][col] + ", ");
            }
            sc++;

            // print ending row from sc to ec
            row = er;
            for(col = sc; col<=ec && sr<=er; col++){
                System.out.print(matrix[row][col] + ", ");
            }
            er--;

            // print ending col from er to sr
            col = ec;
            for(row=er; row>=sr && sr<=er && sc<=ec; row--){
                System.out.print(matrix[row][col] + ", ");
            }
            ec--;

            // print starting row from ec to sc
            row = sr;
            for(col = ec; col>=sc && sr<=er && sc<=ec; col--){
                System.out.print(matrix[row][col] + ", ");
            }
            sr++;

            System.out.println();
        }
    }

    public static void main(String[] args){
        int[][] arr = {{1,6,11,14,21}, {2,7,12,15,25}, {3,8,13,16,22}, {4,9,17,19,24}, {5,10,20,18,23}};

        printSpiral(arr);
    }