ArrayIndexOutOfBounds on enhanced for loop

Question

I am trying to figure out part of an assignment and I have been beating my head against a wall for some time now. I\'m trying to transcribe DNA sequences to RNA sequences. I am,

Answer 1

You want 1 less than size , so : if (pos1 >= linkedList.size()) {.

When pos1 == linkedList.size() it will be out of bounds

Answer 2

The problem is in the statement arr[a] ='U';

The problem is that char is represented as an int internally and 'T' equals 84 hence you get an ArrayIndexOutOfBoundsException. You need to iterate over it with a traditional counter:

for (int i = 0; i < arr.length; i++) {
    if (arr[i] == 'T') {
        arr[i] ='U';
    }
}