Question

In Java

Only can use

• class String
  • length
  • charAt
• class StringBuilder
  • length
  • charAt
  • append
  • toString
• class Character
  • any method

Create the following methods

1. nthWord takes an int and a String as input and returns a String:
   The input int represents a number n that is assumed to be positive, and the output string contains every nth word of the input string, starting with the first word, separated by a single space. {\em For this method, a word is defined to be a sequence of non-space characters.} There should be no space at the end of the output string.

   > HW2.nthWord(3, "zero one    two  three four five six seven")
   "zero three six"
   

2. truncateAfter takes an int and a String as input and returns a String:
   The input string may contain hyphens and spaces that mark appropriate places to truncate the string. The output string will be a truncated version of the input string, and the input int value is the desired length of the output string. The output string should truncate the input string at the first legal spot such that the output string will have at least the desired length. If the truncation happens at a space, the space is not included in the output, but if the truncation happens at a hyphen, the hyphen is included. No other hyphens are included in the output, but the other spaces are. (If the input string does not have enough characters to meet the desired minimum, then the output should be the entire input string without the hyphens.)

   > HW2.truncateAfter(5, "La-te-ly the-re.")
   "Late-"
   > HW2.truncateAfter(6, "La-te-ly the-re.")
   "Lately"
   > HW2.truncateAfter(7, "La-te-ly the-re.")
   "Lately the-"
   

3. truncateBefore: the same as the truncateAfter method, but now the input int value is the maximum, and the string should be truncated at the latest possible point such that the resulting string has no more than the desired length.

Answer 1

public static String nthWord(int n, String sentence) {

    StringBuffer buffer = new StringBuffer();

    String[] words = sentence.split("\\s+");
    int currentIndex = 0;
    while (currentIndex < words.length) {
        buffer.append(words[currentIndex]).append(" ");
        currentIndex += n;
    }
    return buffer.toString().trim();
}

===================================================================================

public static String truncateAfter(int n, String phrase) {

    StringBuffer buffer = new StringBuffer();
    int index = 0;
    int m = n;
    while (n > 1) {
        if (('a' <= phrase.charAt(index) && phrase.charAt(index) <= 'z') ||
                ('A' <= phrase.charAt(index) && phrase.charAt(index) <= 'Z') ||
                ' ' == phrase.charAt(index)) {
            buffer.append(phrase.charAt(index));
            n -= 1;
        }
        index += 1;
    }
    if (phrase.charAt(m) == '-') {
        buffer.append('-');

    } else if (phrase.charAt(index) != ' ') {
        buffer.append(phrase.charAt(index));
    } else {
        while (true) {
            buffer.append(phrase.charAt(index));
            index++;
            if (phrase.charAt(index) == '-') {
                break;
            }
        }
         buffer.append('-').toString();
    }
    return buffer.toString();

}

==============================================================================

public static String truncateBefore(int n, String phrase) {

    StringBuffer buffer = new StringBuffer();
    int index = 0;
    int m = n;
    while (n > 1) {
        if (('a' <= phrase.charAt(index) && phrase.charAt(index) <= 'z') ||
                ('A' <= phrase.charAt(index) && phrase.charAt(index) <= 'Z') ||
                ' ' == phrase.charAt(index)) {
            buffer.append(phrase.charAt(index));
            n -= 1;
        }
        index += 1;
    }
    if (phrase.charAt(m) == '-') {
        buffer.append('-');

    } else if (phrase.charAt(index) != ' ') {
        buffer.append(phrase.charAt(index));
    }
    return buffer.toString();
}