Program to check if a character is a number / digit in Java
package com.hubberspot.example;
public class IsNumberTest {
public static void main(String[] args) {
// Create a String of character having numbers
// in between just for a test
String characters = "q1w2E3r4T5y 6!7@8#9$0%-^";
// we take the length of characters by length()
int length = characters.length();
// we than loop each character one by one
for(int i = 0; i < length; i++) {
// we store each character in a variable
// for each loop
char character = characters.charAt(i);
// checking for each character that its a number or not
// by calling Character class isDigit() method , by passing
// the character. It returns true if the character passed is
// digit or a number
if(Character.isDigit(character)) {
System.out.println("Given character at index " + i + " is a number");
}
else {
System.out.println("Given character at index " + i + " is not a number");
}
}
}
}
Output of the program : 
