how do i use is digit in string java code example

Example: isnumber java

// find value is number or not in java..
// if the value is number output is true 
// if the value is not a number then output is false.. 


public class Test {

   public static void main(String args[]) {
      System.out.println(Character.isDigit('c')); // false 
      System.out.println(Character.isDigit('5')); // true
   }
}