Quarter.java

  1. package edu.ucsb.cs156.courses.models;

  3. import java.util.ArrayList;
  4. import java.util.List;
  5. import java.util.Objects;

  7. /**
  8.  * Represents a UCSB quarter. Allows easy conversion between QYY alphanumeric format (F19, W20, S20,
  9.  * M20) and YYYYQ numerical format (20194, 20201, 20202, 20203) as well as incrementing and
  10.  * decrementing.
  11.  */
  12. public class Quarter {

  14.   private int yyyyq; // YYYYQ where Q = 1, 2, 3 or 4

  16.   public Quarter(int yyyyq) {
  17.     setValue(yyyyq);
  18.   }

  20.   public int getValue() {
  21.     return this.yyyyq;
  22.   }

  24.   public void setValue(int yyyyq) {
  25.     if (invalidQtr(yyyyq))
  26.       throw new IllegalArgumentException(
  27.           "Quarter constructor requires a integer ending in 1,2,3 or 4");
  28.     this.yyyyq = yyyyq;
  29.   }

  31.   /**
  32.    * Construct a Quarter object from a string s, either in QYY or YYYYQ format. If s is of length
  33.    * three, QYY format is expected, if 5 then YYYYQ format is expected. Otherwise an
  34.    * IllegalArgumentException is thrown.
  35.    *
  36.    * @param s Quarter either in QYY or YYYYQ format
  37.    */
  38.   public Quarter(String s) {

  40.     switch (s.length()) {
  41.       case 3:
  42.         this.yyyyq = qyyToyyyyQ(s);
  43.         return;
  44.       case 5:
  45.         this.yyyyq = yyyyqToInt(s);
  46.         return;
  47.       default:
  48.         throw new IllegalArgumentException("Quarter should be in QYY or YYYYQ format");
  49.     }
  50.   }

  52.   public String getYY() {
  53.     return getYY(this.yyyyq);
  54.   }

  56.   public String getYYYY() {
  57.     return getYYYY(this.yyyyq);
  58.   }

  60.   public String getYYYYQ() {
  61.     return String.format("%d", this.yyyyq);
  62.   }

  64.   public String toString() {
  65.     return yyyyqToQyy(this.yyyyq);
  66.   }

  68.   public String getQ() {
  69.     return getQ(this.yyyyq);
  70.   }

  72.   private static boolean invalidQtr(int value) {
  73.     int index = value % 10;
  74.     return (index < 1) || (index > 4);
  75.   }

  77.   /**
  78.    * Advance to the next quarter, and return the value of that quarter as an int.
  79.    *
  80.    * @return the new getValue() for the quarter, i.e. quarter as in in yyyyq format
  81.    */
  82.   public int increment() {
  83.     int q = this.yyyyq % 10;
  84.     int yyyy = this.yyyyq / 10;

  86.     setValue((q == 4) ? (((yyyy + 1) * 10) + 1) : (this.yyyyq + 1));
  87.     return this.yyyyq;
  88.   }

  90.   /**
  91.    * Subtract one from current quarter, and return the value of that quarter as an int.
  92.    *
  93.    * @return the new getValue() for the quarter, i.e. quarter as in in yyyyq format
  94.    */
  95.   public int decrement() {
  96.     int q = this.yyyyq % 10;
  97.     int yyyy = this.yyyyq / 10;

  99.     setValue((q == 1) ? (((yyyy - 1) * 10) + 4) : (this.yyyyq - 1));
  100.     return this.yyyyq;
  101.   }

  103.   /**
  104.    * Convert yyyyq as string to int, throwing exception if format is incorrect
  105.    *
  106.    * @param yyyyq String in yyyyq format (e.g. 20194 for F19 (Fall 2019))
  107.    * @throws IllegalArgumentException
  108.    * @return int representation of quarter
  109.    */
  110.   public static int yyyyqToInt(String yyyyq) {
  111.     String errorMsg =
  112.         "Argument should be a string representation of a five digit integer yyyyq ending in 1,2,3 or 4";
  113.     int result = 0;
  114.     try {
  115.       result = Integer.parseInt(yyyyq);
  116.     } catch (Exception e) {
  117.       throw new IllegalArgumentException(errorMsg);
  118.     }
  119.     if (invalidQtr(result)) {
  120.       throw new IllegalArgumentException(errorMsg);
  121.     }
  122.     return result;
  123.   }

  125.   /**
  126.    * Convert yyyyq int format to Yqq String format throwing exception if format is incorrect
  127.    *
  128.    * @param yyyyq int (e.g. 20194 for Fall 2019
  129.    * @throws IllegalArgumentException
  130.    * @return Qyy representation (e.g. F19)
  131.    */
  132.   public static String yyyyqToQyy(int yyyyq) {
  133.     if (invalidQtr(yyyyq)) {
  134.       throw new IllegalArgumentException(
  135.           "Argument should be a five digit integer in qqqqy format ending in 1,2,3 or 4");
  136.     }
  137.     return String.format("%s%s", getQ(yyyyq), getYY(yyyyq));
  138.   }

  140.   /**
  141.    * Take yyyyq int format and return single character for quarter, either "W", "S", "M", or "F" for
  142.    * last digit 1, 2, 3, 4, respectively. Throw illegal argument exception if not in yyyyq format.
  143.    *
  144.    * @param yyyyq int (e.g. 20194 for Fall 2019)
  145.    * @throws IllegalArgumentException
  146.    * @return single char string for quarter (e.g. "F")
  147.    */
  148.   public static String getQ(int yyyyq) {
  149.     if (invalidQtr(yyyyq)) {
  150.       throw new IllegalArgumentException(
  151.           "Argument should be a five digit integer in qqqqy format ending in 1,2,3 or 4");
  152.     }
  153.     String[] quarters = new String[] {"W", "S", "M", "F"};
  154.     int index = yyyyq % 10;
  155.     return quarters[index - 1];
  156.   }

  158.   /**
  159.    * Take yyyyq int format and return two digit year as a String Throw illegal argument exception if
  160.    * not in yyyyq format.
  161.    *
  162.    * @param yyyyq int (e.g. 20194 for Fall 2019)
  163.    * @throws IllegalArgumentException
  164.    * @return two char string for year (e.g. "19")
  165.    */
  166.   public static String getYY(int yyyyq) {
  167.     if (invalidQtr(yyyyq)) {
  168.       throw new IllegalArgumentException(
  169.           "Argument should be a five digit integer in qqqqy format ending in 1,2,3 or 4");
  170.     }
  171.     return String.format("%02d", (yyyyq / 10) % 100);
  172.   }

  174.   /**
  175.    * Take yyyyq int format and return four digit year as a String Throw illegal argument exception
  176.    * if not in yyyyq format.
  177.    *
  178.    * @param yyyyq int (e.g. 20194 for Fall 2019)
  179.    * @throws IllegalArgumentException
  180.    * @return four char string for year (e.g. "2019")
  181.    */
  182.   public static String getYYYY(int yyyyq) {
  183.     if (invalidQtr(yyyyq)) {
  184.       throw new IllegalArgumentException(
  185.           "Argument should be a five digit integer in qqqqy format ending in 1,2,3 or 4");
  186.     }
  187.     return String.format("%04d", (yyyyq / 10));
  188.   }

  190.   public static int qyyToyyyyQ(String qyy) {
  191.     if (qyy.length() != 3) throw new IllegalArgumentException("Argument should be in QYY format");

  193.     char q = qyy.charAt(0);
  194.     String yy = qyy.substring(1, 3);
  195.     String legalQuarters = "WSMF";
  196.     int qInt = legalQuarters.indexOf(q) + 1;
  197.     if (invalidQtr(qInt)) {
  198.       throw new IllegalArgumentException("First char should be one of " + legalQuarters);
  199.     }
  200.     int yyInt = Integer.parseInt(yy);
  201.     int century = (yyInt > 50) ? 1900 : 2000;
  202.     return (century + yyInt) * 10 + qInt;
  203.   }

  205.   @Override
  206.   public boolean equals(Object o) {
  207.     if (o == this) return true;
  208.     if (!(o instanceof Quarter)) {
  209.       return false;
  210.     }
  211.     Quarter quarter = (Quarter) o;
  212.     return yyyyq == quarter.yyyyq;
  213.   }

  215.   @Override
  216.   public int hashCode() {
  217.     return Objects.hashCode(yyyyq);
  218.   }

  220.   /**
  221.    * return a list of Quarters starting with the start parameter and ending with the end parameter,
  222.    * inclusive.
  223.    *
  224.    * <p>The result will automatically go in chronological or reverse chronological order, depending
  225.    * on the order of the parameters.
  226.    *
  227.    * @param start
  228.    * @param end
  229.    * @return list of quarters in specified order
  230.    */
  231.   public static List<Quarter> quarterList(String start, String end) {
  232.     List<Quarter> result = new ArrayList<Quarter>();

  234.     int startInt = Quarter.yyyyqToInt(start);
  235.     int endInt = Quarter.yyyyqToInt(end);

  237.     if (startInt < endInt) {
  238.       for (Quarter iter = new Quarter(startInt); iter.getValue() <= endInt; iter.increment()) {
  239.         Quarter q = new Quarter(iter.getValue());
  240.         result.add(q);
  241.       }
  242.     }
  243.     if (startInt >= endInt) {
  244.       for (Quarter iter = new Quarter(startInt); iter.getValue() >= endInt; iter.decrement()) {
  245.         Quarter q = new Quarter(iter.getValue());
  246.         result.add(q);
  247.       }
  248.     }
  249.     return result;
  250.   }
  251. }
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