How to check if a character is a digit in Java

Overview

We can check if a character is a digit in Java without using any built-in method. A digit character is any numeric character from 0 and 9. The way to achieve this is by using an if-else condition.

Syntax

if(character <= '0' && character >= '9'){
    // character is digit
}else{
    // character is not digit 
}
Check if a character is a digit in Java

Parameter

character: This is the character that we're checking to see if it is a digit or not.

Code example

class HelloWorld {
    // create function to check if digt
    static void checkIfDigit(char character){
      if (character >= '0' & character <= '9'){
        System.out.println(character +" is digit");
      }else{
        System.out.println(character +" is not digit");
      }
    }
    public static void main( String args[] ) {
        // check if some characters are digits
        checkIfDigit('e');
        checkIfDigit('1');
        checkIfDigit('3');
        checkIfDigit('%');
        checkIfDigit('4');
    }
}

Explanation

In the code above:

  • Line 3: We create a function to check if a character is a digit character. It takes a character as a parameter and applies the above condition.
  • Lines 12–16: With the function we created, we check several characters to see if they are digits and print the results to the console.
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