title: Check non-numeric characters in string
body: <p>I want to check whether the String contains only numeric characters or it contains alpha-numeric characters too.</p>
  
  <p>I have to implement this check in database transaction where about a hundred-thousand records are going to be fetched and passed through this check, so I need optimized performance answer.</p>
  
  <p>Currently, I have implemented this through a try-catch block: I parsed the string in Integer in try block and checked for the NumberFormatException in the catch block. Please suggest if I'm wrong.</p>