Question

Let’s say, I have some user input (as a String) like “11010011011”.

Now I want to check if a bit at a bit at a particular position is set (each digit should act as a flag).

Note: I am receiving the user’s input as a String.

How can I do that?

Answer 1

You could work with the string as is – say you want to check the first bit on the left:

if (input.charAt(0) == '1') { //

Alternatively if you want to work with a BitSet you can initialise it in a loop:

String input = "11010011011";
BitSet bs = new BitSet(input.length());
int i = 0;
for (char c : input.toCharArray()) {
    if (c == '1') bs.set(i);
    i++;
}

Then to check if the i-th bit is set:

boolean isSet = bs.get(i);