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Java Simplified. Extensions and Useful Constructs for the Java Platform. Codeprimate Elements (a.k.a. cp-elements) is a Java library and micro-framework used to simplify the development of software applications written in Java. Elements packages several APIs into one library in order to address various application concerns and aspects of software design and development collectively and conveniently. Elements is a highly simple, yet robust and proven library built on solid OO principles, software design patterns and best practices to effectively solve common and reoccurring problems in software development.

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/*
 * Copyright 2016 Author or Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.cp.elements.lang;

import java.util.Calendar;

/**
 * The DateTimeUtils class contains common functionality for working with dates and time.
 * 
 * @author John J. Blum
 * @see java.util.Calendar
 * @see java.util.Date
 * @see java.sql.Time
 * @see java.sql.Timestamp
 * @since 1.0.0
 */
@SuppressWarnings("unused")
public abstract class DateTimeUtils {

  public static final int NUMBER_OF_MILLISECONDS_IN_SECOND = 1000;
  public static final int NUMBER_OF_SECONDS_IN_MINUTE = 60;
  public static final int NUMBER_OF_MINUTES_IN_HOUR = 60;
  public static final int NUMBER_OF_HOURS_IN_DAY = 24;
  public static final int NUMBER_OF_DAYS_IN_FEBRUARY_OF_LEAP_YEAR = 29;
  public static final int NUMBER_OF_DAYS_IN_WEEK = 7;
  public static final int NUMBER_OF_DAYS_IN_YEAR = 365;
  public static final int NUMBER_OF_DAYS_IN_LEAP_YEAR = 366;
  public static final int NUMBER_OF_MONTHS_IN_YEAR = 12;
  public static final int NUMBER_OF_YEARS_IN_DECADE = 10;
  public static final int NUMBER_OF_YEARS_IN_SCORE = 20;
  public static final int NUMBER_OF_YEARS_IN_CENTURY = 100;
  public static final int NUMBER_OF_YEARS_IN_MILLENNIUM = 1000;

  public static final int[] NUMBER_OF_DAYS_IN_MONTH = {
    31, // January
    28, // February
    31, // March
    30, // April
    31, // May
    30, // June
    31, // July
    31, // August
    30, // September
    31, // October
    30, // November
    31  // December
  };

  /**
   * Clones the specified Calendar object if not null, otherwise if the date and time value is null
   * then this method returns null.
   * 
   * @param dateTime the Calendar object to clone.
   * @return a clone of the specified Calendar object if the Calendar is not null, otherwise return null.
   * @see java.util.Calendar#clone()
   */
  public static Calendar clone(final Calendar dateTime) {
    return (dateTime == null ? null : (Calendar) dateTime.clone());
  }

  /**
   * Creates a Calendar instance with a date and time set to the time in milliseconds.
   * 
   * @param timeInMilliseconds a long value indicating the number of milliseconds since the EPOCH.
   * @return a Calendar instance initialized with the specified date/time in milliseconds.
   * @see java.util.Calendar
   */
  public static Calendar create(final long timeInMilliseconds) {
    Calendar dateTime = Calendar.getInstance();
    dateTime.clear();
    dateTime.setTimeInMillis(timeInMilliseconds);
    return dateTime;
  }

  /**
   * Truncates the time portion of the Calendar's date/time components.  If the Calendar object is null, then null
   * is returned.  The fields of the Calendar to be truncated include the hour of day, minute, second and milliseconds.
   * 
   * @param dateTime the Calendar object to truncate.
   * @return the Calendar object with the time portion truncated (the corresponding time fields of this Calendar
   * are set to zero).
   * @see java.util.Calendar
   */
  public static Calendar truncate(final Calendar dateTime) {
    if (dateTime != null) {
      dateTime.clear(Calendar.HOUR_OF_DAY);
      dateTime.clear(Calendar.MINUTE);
      dateTime.clear(Calendar.SECOND);
      dateTime.clear(Calendar.MILLISECOND);
    }

    return dateTime;
  }

}