String regex = "[hc]at"; 
    String input = "The cat wears a hat.";
    System.out.println("Regex: " + regex);
    System.out.println("Input: " + input);
	
    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(input);
		
    boolean found = false;
    while (matcher.find()) {
        System.out.println("Found '" + matcher.group() + 
                           "' from " + matcher.start() + 
                           " to " + matcher.end());
        found = true;
    }

    if(!found)
        System.out.println("No match found!");

    Regex: [hc]at
    Input: The cat wears a hat.
    Found 'cat' from 4 to 7
    Found 'hat' from 16 to 19

    String regex = "\\d{3}-\\d{3}-\\d{4}"; 
    String input = "415-555-1234";
    System.out.println("Regex: " + regex);
    System.out.println("Input: " + input);
  		
    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(input);
  		
    if (matcher.matches()) {
        System.out.println("Match!");
    } else {
        System.out.println("Does not match!");
    }

    Regex: \d{3}-\d{3}-\d{4}
    Input: 415-555-1234
    Match!