public String toString() {
    StringBuilder sb = new StringBuilder("LimitFilter: (");
    sb.append(this.m_filter)
      .append(" [pageSize=")
      .append(this.m_cPageSize)
      .append(", pageNum=")
      .append(this.m_nPage);
    if (this.m_comparator instanceof ValueExtractor) {
      ValueExtractor extractor = (ValueExtractor)this.m_comparator;
      sb.append(", top=")
        .append(extractor.extract(this.m_oAnchorTop))
        .append(", bottom=")
        .append(extractor.extract(this.m_oAnchorBottom));
    } else if (this.m_comparator != null) {
      sb.append(", comparator=")
        .append(this.m_comparator);
    } 
    sb.append("])");
    return sb.toString();
  }

  public E extract(T oTarget) {
    if (oTarget == null)
      return null; 
    Class<?> clz = oTarget.getClass();
    try {
      Method method = this.m_methodPrev;
      if (method == null || method.getDeclaringClass() != clz)
        this.m_methodPrev = method = ClassHelper.findMethod(clz, 
            getMethodName(), ClassHelper.getClassArray(this.m_aoParam), false); 
      return (E)method.invoke(oTarget, this.m_aoParam);
    } catch (NullPointerException e) {
      throw new RuntimeException(suggestExtractFailureCause(clz));
    } catch (Exception e) {
      throw ensureRuntimeException(e, clz
          .getName() + this + '(' + oTarget + ')');
    } 
  }

private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
        ObjectInputStream.GetField gf = ois.readFields();
        Object valObj = gf.get("val", null);

        if (valObj == null) {
            val = null;
        } else if (valObj instanceof String) {
            val= valObj;
        } else if (System.getSecurityManager() == null
                || valObj instanceof Long
                || valObj instanceof Integer
                || valObj instanceof Float
                || valObj instanceof Double
                || valObj instanceof Byte
                || valObj instanceof Short
                || valObj instanceof Boolean) {
            val = valObj.toString();
       ...
    }