Help!! How to accept numeric input characters only

Question

How do I incorporate my isInputStringNumeric(String s) into my while loop; I am having a problem with this specific area.
System.out.println("Enter Input Currency Value:");
System.out.println("Select currency: ");
public static boolean isInputStringNumeric(String s)
//looping structure to check from the first character to the last of the value entered
int stringSize = s.length();
for (int i = 0; i < stringSize; i++)
boolean check = Character.isDigit(s.charAt(i));
if (!check)
return false;//if any characters at each position of the string's length is not a digit
return true;//if any characters at each position of the string's length is a digit
}//end of isInputStringNumeric function
float inputCurrencyValue = float.parseFloat( inputString() );
//Error message if a user enter a non-digit
while (inputCurrencyValue = (inputString()) != null)
if( isInputStringNumeric(inputString()) == false )
System.out.println("Invalid Characters entered");
System.out.println("Please enter a numerical value");
inputCurrencyValue = ( inputString() );

Answer 1

Replace your isInputStringNumeric method with this regular expression that checks the string for characters 0-9. If s contains anything else (or nothing!), false is returned.
Here's some code to test with.
import java.util.regex.*;
public class Junk1 {
    public static void main(String[] args) {
        String s = "12345";
        if (Pattern.matches("\\d+", s)) {
            System.out.println("Is a number");
        } else {
            System.out.println("No input or not a number");