public class CodeWordChecker implements StringChecker
{
  private int min;
  private int max;
  private String notOccur;
  
  public CodeWordChecker(int min, int max, String notOccur)
  {
    this.min = min;
    this.max = max;
    this.notOccur = notOccur;
  }
  public CodeWordChecker(String notOccur)
  {
    min = 6;
    max = 20;
    this.notOccur = notOccur;
  }
  public boolean isValid(String str)
  {
    return (str.length() >= min) && (str.length <= max) && (str.indexOf(notOccur) == -1);
  }
}