Validating user input in java

// instantiate the Validator class
Validator validator = new Validator();

// call whichever method you want to use - depending on what your validating
// here I'm just checking that the string contains numbers only

if(!validator.checkNumber(numberString)){
      // do something if you fancy
      return;
}

// you'll only get this far if the validation was successful


And here's a copy of the full Validator class definition:

import java.util.regex.*;

/*
 * Validator.java
 */

/**
 * $Id$
 * @author  Administrator
 */

public class Validator {
    private String regex;
    private Pattern pattern;
    private Matcher matcher;
    
    /** Creates a new instance of Validator */
    public Validator() {
    }
    
    public boolean checkName(String name){
        //System.out.println(" sent in name string: "+name);
        regex = ".*[^s]{1,}.*"; // anything, then at least one non whitespace charater, then anything
        pattern = Pattern.compile(regex);
        return(pattern.matcher(name).matches());
    }
    
    public boolean checkNumber(String number){
        /* check that there is a valid number */
        regex = ".*d+.*"; // any numbers (greedy & lazy)
        pattern = Pattern.compile(regex);
        return(pattern.matcher(number).matches());
    }
    
    public boolean checkEmail(String email){
        /* check that there is a valid number */
        pattern = Pattern.compile(".+@.+.[a-z]+"); // inclusive character class
        if(!pattern.matcher(email).matches()){
            // no valid characters
            return false;
        }else{
            return true;
        }        
    }
}