Question

I print to the standard output some characters from a wide UTF-8 range in a Java application. My console is configured for UTF-8 support. My problem is that sometimes, when I decide to print 10 characters for example, I see a number of character which is less then 10.

I think this is due to the console which interprets some characters. Are there some unicode character which can be interpreted like: erase the previous character ? Is it possible to exclude them from the ouput (what are the codepoints of these characters)?

Answer 1

Using carriage return or the backspace character you can get results like you describe. This little test program for instance…

public class Test {
    public static void main(String... args) {
        System.out.println("abc\rdef\u0008g");
    }
}

…prints in my terminal (ubuntu)

$ java Test
deg
$

\r is carriage return, and \u0008 represents the backspace character. (Carriage return sends the cursor back to the first column, and backspace sends it back one column.)

---

To remove all these, so called “control characters” you could do:

myString = myString.replaceAll("\\p{Cntrl}", "");

from the docs:

\p{Cntrl}      A control character: [\x00-\x1F\x7F]