As already written you have to put your next element in a local variable.
This is not enough however: please never use ==
to compare strings. Use String's method equals
instead or even equalsIgnoreCase
.
You should use something like :
String val = j.next();
if(val.equals("A")){ // you could use val.equalsIgnoreCase("A") to be case insensitive
...
} else if (val.equals("B")){
...
As suggested in aljipa's answer, you you to use a switch. If you want your test to be case insensitive can can also write something like:
String val = j.next();
switch (val.toUpperCase()) {
case "A":
a++;
break;
case "B":
...