How to set integer and string range from string in Java

The input given is Integer + String, however I want to set a range of integer input (1~34) and String (A~F).
if I do,

int i = (Integer.parseInt(input));

if (n > 34) {
    System.out.println("number too high");
}

it gives me

Exception in thread "main" java.lang.NumberFormatException: For input string: "35A"

is there any way to make this work? thanks in advace

if the string is 1A to 34F it should pass, anything over that should fail.. please help!

If you are trying to parse a hexadecimal string, pass a radix argument:

Integer.parseInt(input, 16)

If it's not hexadecimal, you need to separate the String into the number part and other part first (can't tell you how since you haven't told us what the options are), and then only pass the String containing numbers to Integer.parseInt.

You could first split the String into number and letter

String[] split = n.split("(?=[A-Z])");

then check if the two parts fit your needs

if(Integer.parseInt(split[0]) > 34 || split[1].charAt(0) > 'F') {
    System.out.println("number too high");
}

You'd have to check beforehand that your String actually conforms to that pattern but you said in the comments that it's always in that format, so it should work. Also if lowercase letters are possible you have to change the regex and condition or simply call toUppercase() on the input String.

I am using the regular expression to solve the problem:

 String patternString="(0{0,1}[1-9][A-F])|([1-2]{1}\\d{1}[A-F]{1})|(3{1}[0-4]{1}[A-F]{1})";
    String data[]={"34f","00F","01F","1a","1A","26b"};
    
    for (int i=0;i < data.length;i++){
        System.out.println(data[i]+":"+Pattern.matches(patternString, data[i]));
    }

 //expected result"
 //34f:false
 //00F:false
 //01F:true
 //1a:false
 //1A:true
 //26b:false

I would recommend you to use regex.

boolean result2 = Pattern.matches("[0-3][0-4]?[A-F]", "34A"); // Compiles and matches pattern

System.out.println(result2);

This pattern will fulfill your requirement.

You can use regex with grouping to easily extract data from the string:

public class RandomStuff {

  public static void main(String[] args) {
    String string = "34F";
    Pattern pattern = Pattern.compile("(\\d{1,2})([A-F])");
    Matcher matcher = pattern.matcher(string);
    if (!matcher.find()) {
      System.out.println("does not match pattern, do whatever is needed");
      //stop execution however applicable for use case
    }
    int number = Integer.parseInt(matcher.group(1));
    if (number < 1 || number > 34) {
      System.out.println("number not in range");//or other message
    }
    // no need to validate letters
  }
}

(\\d{1,2}) - matches 1 or 2 numbers (0 to 99) and captures it as group 1.

([A-F]) matches a single letter (A, B, C, D, E or F) and captures result as group 2. If lower case letters are valid as well, you can add a case insensitive flag or add character set for lower letters as well - [a-f], to this group.

Check the last character.And you can catch NumberFormatException when the parseInt gets an exception without last character.

    String input = "34F";
    char lastc = input.charAt(input.length()-1);

    if(lastc >= 'A' && lastc <= 'F'){
        try{
            int n = (Integer.parseInt(input.substring(0,input.length()-1)));

            if (n > 34 || n < 1) {
                System.out.println("number not in range");
            }
        } catch(NumberFormatException e1){
            System.err.println("input error.check it.");
        }
    }else{
        System.err.println("input error.check it.");
    }