switch(firstChar) {
case ‘N’:
nextFirstChar = ‘O’;
break;
case ‘O’:
nextFirstChar = ‘P’;
break;
case ‘P’:
nextFirstChar = ‘Q’;
break;
case ‘Q’:
nextFirstChar = ‘R’;
break;
case ‘R’:
nextFirstChar = ‘S’;
break;
case ‘S’:
nextFirstChar = ‘T’;
break;
case ‘T’:
throw new IllegalArgument();
default:
}