Double Maintenance Defect Example

/** Find the defect in this code, caused by the "double maintenance" problem */

// "right-click" is simulated by prefix period character
boolean rightclick = false;
if (line.charAt(0) == '.')
{
    rightclick = true;
    line = line.trim().substring(1,3);
}
// parse the move
char letter = Character.toUpperCase(line.trim().charAt(0));
int row = letter - 'A';
String column = line.trim().substring(1, line.length());
int col = Integer.parseInt(column) - 1;  // zero-base