I need to test if a string is an Hexadecimal value

Question

I'm starting with Android Studio and making a simple App that take an input from am EditText and check if have four characters long(the easy part) and if the whole string is an hexadecimal value like "FFA1".

I think in to add the "0x" to the String but that use more resources a far a read in another post/questions. I also read that exist a library called TextUtils with a function isDigitsOnly() but I'm not sure if they call digits to 0-9 values or 0-9 and A-F too.

In VB.NET I use to add &H to the String and use isNumeric() function to detect Hexa values, but in android I'm lost.

Can somebody enlighten me? Thanks.

Did you type your title into google? Many answers like this: http://stackoverflow.com/questions/11424540/verify-if-string-is-hexadecimal OR http://stackoverflow.com/questions/21992023/check-hex-string-contains-only-hex-bounded-values. Why won't those work? — Rick S, Nov 07 '16 at 15:26
__But in android I'm lost__ . You need to say **Java** instead. — Nabin, Nov 07 '16 at 15:28
@RickS No, I use "android studio is hexadecimal" instead and get a lot of code about colors. — E_Blue, Nov 07 '16 at 15:32
I gave you two solutions. The language you are using is java, so you should be searching for java code. Android studio is not a language. — Rick S, Nov 07 '16 at 15:34
@NabinKhadka Probably yes but since I'm starting with Android and I'm not an expert in JAVA code I don't know if all the libraries, methods and functions are compatible between both. — E_Blue, Nov 07 '16 at 15:36
@RickS I see some examples with regex but I never use regex and I don't want to just copy&paste, of course it works but I want to know why. I mean, since I'm learning something new I want to be able to create my own regex if I need it. Now I will make some research about regex. Thanks for your input. — E_Blue, Nov 07 '16 at 15:40
Probably Check [this](http://stackoverflow.com/questions/5317320/regex-to-check-string-contains-only-hex-characters) — ADM, Nov 07 '16 at 16:03

score 0 · Answer 1 · answered Nov 07 '16 at 22:42

You should to test with this void:

private void test(){     
     try{
String hex = "Your String"
int hexadecimalValue = Integer.parseInt(hex, 16);  
System.out.println("valid hexadecimal");
}  catch(NumberFormatException e){
// not a valid hex
System.out.println("not a valid hexadecimal");
}}

I need to test if a string is an Hexadecimal value

1 Answers1