utilities.java

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/*
 * @author                        : Neelesh
 * @Version                       : 2.0
 *
 * Development Environment        : Oracle9i JDeveloper
 * Name of the File               : Utilities.java
 * Creation/Modification History  :
 *
 * Neelesh  06-Jan-2003      Created
 *
 */
package oracle.otnsamples.util;


// Exception class
import java.io.IOException;

import java.text.NumberFormat;
import java.text.SimpleDateFormat;

import java.util.Date;
import java.util.Enumeration;
import java.util.Locale;

// Java utility classes 
import java.util.Properties;
import java.util.ResourceBundle;


/**
 * This class implements a set of utility methods used by other modules of
 * virtual shopping mall application.
 *
 * @author Neelesh
 * @version 2.0
 */
public final class Utilities {

  // Default Minimum Fractional digits
  private static final int MIN_DIGITS = 2;

  // Default Maximum Fractional digits
  private static final int MAX_DIGITS = 2;

  // Default date format
  private static final String DATEFORMAT = "MM/dd/yyyy";

  /**
   * Method to format a date object to a string of supplied format If the
   * format is null, the default mm-dd-yyyy is assumed Returns null if the
   * format string is invalid.
   *
   * @param <b>date </b>The date object to be formatted
   * @param <b>format </b> The date format
   *
   * @return <b>date</b> The string representation of date
   */
  public static String format(Date date, String format) {

    return format(date, format, null);
  }
  /**
   * Method to format a date object to a string of supplied format and locale
   * If the format is null, the default mm-dd-yyyy is assumed if locale is
   * null, the default locale of the system is assumed Returns null if the
   * format string is invalid.
   *
   * @param <b>date </b>The date object to be formatted
   * @param <b>format </b> The date format
   * @param <b>locale </b> The locale
   *
   * @return <b>date</b> The string representation of date
   */
  public static String format(Date date, String format, Locale locale) {

    try {

      if(format == null) {
        format = DATEFORMAT;
      }

      if(locale == null) {
        locale = Locale.getDefault();
      }

      SimpleDateFormat sdf = new SimpleDateFormat(format, locale);

      return sdf.format(date);

    } catch(Exception ex) {
      throw new UtilityException("Exception thrown from format " +
                                 "method of Utilities class : " +
                                 ex.getMessage());
    }
  }
  /**
   * Method to format a double to a currency based on supplied locale. If
   * locale is null, the default locale of the system is assumed Returns
   * String representation of the value passed if an error is encountered.
   *
   * @param <b>value </b>The double value to be formatted
   * @param <b>locale </b> The locale
   *
   * @return <b>String</b> The formatted string representation of double value
   */
  public static String currencyFormat(double value, Locale locale) {

    try {

      return NumberFormat.getCurrencyInstance((locale == null)
                                              ? Locale.getDefault() : locale)
                         .format(value);
    } catch(Exception ex) {

      return String.valueOf(value);
    }
  }
  /**
   * Method to format a double to a string based on supplied locale. If locale
   * is null, the default locale of the system is assumed Returns default
   * String representation of the value passed if an error is encountered.
   *
   * @param <b>value </b>The double value to be formatted
   * @param <b>locale </b> The locale
   *
   * @return <b>String</b> The formatted string representation of double value
   */
  public static String format(double value, Locale locale) {

    try {

      return NumberFormat.getInstance((locale == null) ? Locale.getDefault()
                                                       : locale).format(value);
    } catch(Exception ex) {

      return String.valueOf(value);
    }
  }
  /**
   * Method to round a double value to the given precision.
   *
   * @param <b>val </b> The double to be rounded
   * @param <b>precision </b> Rounding precision
   *
   * @return <b>double</b> The rounded value
   */
  public static double round(double val, int precision) {

    // Multiply by 10 to the power of precision and add 0.5 for rounding up
    // Take the nearest integer smaller than this value
    val = Math.floor((val * Math.pow(10, precision)) + 0.5);

    // Divide it by 10**precision to get the rounded value
    return val / Math.pow(10, precision);
  }
  /**
   * Method to format a double value to a string.
   *
   * @param <b>value </b>The date object to be formatted
   * @param <b>minDigits </b>The date object to be formatted
   * @param <b>maxDigits </b>The date object to be formatted
   *
   * @return <b>value</b> The string representation of the double value passed
   */
  public static String format(double value, int minDigits, int maxDigits) {

    // Number format class to format the values
    NumberFormat numFormat = NumberFormat.getInstance();
    numFormat.setMinimumFractionDigits(minDigits);
    numFormat.setMaximumFractionDigits(maxDigits);

    return numFormat.format(value);
  }
  /**
   * This method reads a properties file, which is passed as the parameter to
   * it and load it into a java Properties object and returns it.
   *
   * @param <b>file </b> Represents the .properties file
   *
   * @return <b>Properties</b>The properties object
   *
   * @throws <b>IOExceptionIOException </b> The exception this method can throw
   */
  public static Properties loadParams(String file)
                               throws IOException {

    // Loads a ResourceBundle and creates Properties from it
    Properties prop       = new Properties();
    ResourceBundle bundle = ResourceBundle.getBundle(file);

    Enumeration enum = bundle.getKeys();
    String key       = null;

    while(enum.hasMoreElements()) {
      key = (String) enum.nextElement();
      prop.put(key, bundle.getObject(key));
    }

    return prop;
  }
  /**
   * This method reads a properties file, which is passed as the parameter to
   * it and load it into a java Properties object and returns it.
   *
   * @param <b>file </b> Represents the .properties file
   *
   * @return <b>Properties</b>The properties object
   *
   * @throws <b>IOExceptionIOException </b> The exception this method can throw
   */
  public static Properties loadParams(String file, String language)
                               throws IOException {

    // Loads a ResourceBundle and creates Properties from it
    Properties prop       = new Properties();
    ResourceBundle bundle =
      ResourceBundle.getBundle(file, new Locale(language, ""));

    Enumeration enum = bundle.getKeys();
    String key       = null;

    while(enum.hasMoreElements()) {
      key = (String) enum.nextElement();
      prop.put(key, bundle.getObject(key));
    }

    return prop;
  }
  /**
   * Method to parse a date string in the format mm-dd-yyyy to a Date object
   * This method returns null if the input string does not match the format.
   *
   * @param <b>dateString </b> The string to be converted to a Date
   *
   * @return <b>Date</b>The parsed date object
   */
  public static Date parse(String dateString) {

    return parse(dateString, null);
  }
  /**
   * Method to parse a date string in the supplied format to a Date object. If
   * the format is null, the default mm-dd-yyyy is assumed and returns null if
   * the input string does not match the format.
   *
   * @param <b>dateString </b> The string to be converted to a Date
   * @param <b>formatString </b> The format of the string
   *
   * @return <b>Date</b> The Date object of the string parsed
   */
  public static Date parse(String dateString, String formatString) {

    try {

      if(formatString == null) {
        formatString = DATEFORMAT;
      }

      SimpleDateFormat sdf = new SimpleDateFormat(formatString);

      return sdf.parse(dateString);
    } catch(Exception ex) {
      throw new UtilityException("Exception thrown from parse " +
                                 "method of Utilities class of given " +
                                 "status : " + ex.getMessage());
    }
  }
  /**
   * Method to format a date object to a mm-dd-yyyy string.
   *
   * @param <b>date </b>The date object to be formatted
   *
   * @return <b>date</b> String representation of date
   */
  public static String format(Date date) {

    return format(date, null);
  }
  /**
   * Method to format a double value to a string.
   *
   * @param <b>value </b>The date object to be formatted
   *
   * @return <b>String</b> The string representation of the double value
   */
  public static String format(double value) {

    // Number format class to format the values
    NumberFormat numFormat = NumberFormat.getInstance();
    numFormat.setMinimumFractionDigits(MIN_DIGITS);
    numFormat.setMaximumFractionDigits(MAX_DIGITS);

    return numFormat.format(value);
  }
}