Question

I am trying to replace a single character (bit) in a string, which is a binary number. For bit replacement i have designed a method, which simply partition the string using string.substring() method accoring to the given index then concatenates all. Below is the method-

    /*
     *Method will replace the index-th bit with bitToInsert in the given str
     */
    String str = "11000110100110011111"; 
    int index = 5;
    int bitToInsert = 0;
    if (index == 0) {
        str = str.substring(0, str.length() - 1) + bitToInsert;
    } else {
        str = str.substring(0, str.length() - index - 1) + bitToInsert + str.substring(str.length() - index);
    }

This works fine, however this takes very much time to replace a bit, when given str is very large. Is there any other way, so that replacement of any bit can be done in much less time compare to the above method?

Answer 1

If you use StringBuffer instead of String you can do this:

StringBuffer sb = new StringBuffer("11000110100110011111");
sb.setCharAt(index, '0');