Block input if it's not the letter "A"

Question

How can I do that if the user is not typing A, then there will not be any output? I want to do this in a EditText.

Code:

InputFilter filter = new InputFilter() { 
            public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { 
                    for (int i = start; i < end; i++) { 
                            if (!Character.toString(source.charAt(i)).equals("a")) { 
                                    return ""; 
                            } 
                    } 
                    return null; 
            } 
        };

@BartWesselink without typing how an EditText have characters in it — Pragnani, Mar 13 '13 at 17:46

jcw · Accepted Answer · 2013-03-13T19:08:22.387

1

You could do it the way that you are attempting to, with an input filter, but I would recommend that you do it in XML instead, by giving your edittext the attribute android:digits="Aa". That should solve your problem.

If you need to use an input filter try this (it is untested and may not work an better than yours)

InputFilter filter = new InputFilter() { 
            public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { 
                    String chars = "";
                    for (int i = start; i < end; i++) { 
                            if (Character.toString(source.charAt(i)).equals("a")) { 
                                    chars = chars + source.charAt(i);
                            } else {
                                //don't add anything to the char sequence
                            }
                    } 
                    return chars; 
            } 
        };

edited Mar 13 '13 at 19:08

answered Mar 13 '13 at 18:09

jcw

5,132
7
45
54

A was for example, it's always an other letter. Sorry – Bart Wesselink Mar 13 '13 at 18:11
@BartWesselink - try the code that I added, it might work – jcw Mar 13 '13 at 18:24
Huh, it doesn't work.. (In the emulator I use the keyboard of my laptop) – Bart Wesselink Mar 13 '13 at 18:32
@BartWesselink - I updated the code, what didn't work? – jcw Mar 13 '13 at 19:09
No. I don't see why it isn't working... – Bart Wesselink Mar 14 '13 at 17:34
Ah now I see why it isn't working, it was my mistake! I put the filter on the textview.. – Bart Wesselink Mar 14 '13 at 17:46

Block input if it's not the letter "A"

1 Answers1