code: public double getDouble(int index) throws JSONException {
      Object o = get(index);
      try {
        return o instanceof Number ? ((Number) o).doubleValue() : Double.valueOf((String) o).doubleValue();
      } catch (Exception e) {
        throw new JSONException("JSONArray[" + index + "] is not a number.");
      }
    }
docs: Get the double value associated with an index.
  
  @param index
  The index must be between 0 and length() - 1.
  @return The value.
  @throws JSONException
  If the key is not found or if the value cannot be converted to a number.