001 package example;
002
003 /**
004 * The class to demonstrate ComTest as a test and design tool.
005 * In this example we have side effect that makes
006 * the testing a bit more complex.
007 *
008 * Suppose our problem is to do some linguistic research
009 * and find what are the most popular three first vowels from
010 * every verse in Finish national poetry Kalevala.
011 * The first song of Kalevala begins like:
012 * <pre>
013 * Mieleni minun tekevi, aivoni ajattelevi
014 * lähteäni laulamahan, saa'ani sanelemahan,
015 * sukuvirttä suoltamahan, lajivirttä laulamahan.
016 * Sanat suussani sulavat, puhe'et putoelevat,
017 * kielelleni kerkiävät, hampahilleni hajoovat.
018 * </pre>
019 * At the beginning we will need to read the file kalevala.txt
020 * and then take every verse and extract there 3 first vowels.
021 * To extract the 3 first vowels we might need a function
022 * extract3FirstVowels(s). But to make it a bit more generic
023 * we may send the number 3 as a parameter. And to make it more general
024 * we might send also the list of chars to extract as a parameter.
025 * So we need a function extractChars(s,n,letters)
026 * @author vesal
027 * @version 8.6.2010
028 *
029 */
030 public class TakeCharsReady {
031
032 /**
033 * Take from s the n first chars that are in the list of letters and return them.
034 * @param s where to take letters
035 * @param n how many letters to take at max
036 * @param letters set of letters we are looking
037 * @return n first chars belonging to set letters
038 *
039 * @example
040 * <pre name="test">
041 * StringBuilder s = new StringBuilder("Mieleni minun tekevi");
042 * extractChars(s,3,"aeiouyåäö") === "iee"; s.toString() === "Mlni minun tekevi";
043 * extractChars(s,3,"xyz") === ""; s.toString() === "Mlni minun tekevi";
044 * extractChars(s,4,"klmn") === "Mlnm"; s.toString() === "i inun tekevi";
045 * extractChars(s,4,"e") === "ee"; s.toString() === "i inun tkvi";
046 * </pre>
047 *
048 * @example
049 * <pre name="test">
050 * StringBuilder s;
051 * s = new StringBuilder($s);
052 * extractChars(s,$n,$letters) === $result; s.toString() === $left;
053 *
054 * $s | $n | $letters | $result | $left
055 * -------------------------------------------------------------------------------
056 * "Mieleni minun tekevi" | 3 | "aeiouyåäö" | "iee" | "Mlni minun tekevi"
057 * --- | 3 | "xyz" | "" | "Mlni minun tekevi"
058 * --- | 4 | "klmn" | "Mlnm" | "i inun tekevi"
059 * --- | 4 | "e" | "ee" | "i inun tkvi"
060 * </pre>
061 */
062 public static String extractChars(StringBuilder s, int n, String letters) {
063 StringBuilder result = new StringBuilder();
064 String uletters = letters.toUpperCase();
065 int i = 0;
066 while ( i < s.length() && result.length() < n ) {
067 char c = s.charAt(i);
068 if ( uletters.indexOf(Character.toUpperCase(c)) >= 0 ) { // found the letter
069 result.append(c);
070 s.deleteCharAt(i);
071 } else { // not found, move to the next one
072 i++;
073 }
074 }
075
076 return result.toString();
077 }
078
079 /**
080 * @param args not used
081 */
082 public static void main(String[] args) {
083 StringBuilder s = new StringBuilder("Mieleni minun tekevi");
084 String vowels3 = extractChars(s,3,"aeiouyåäö");
085 System.out.println("Three first vovels are " + vowels3 + " and there are left " + s);
086 }
087
088 }