sort.java

Beginning Java 2, SDK 1.4 Edition Exercise Code samples for this book

//Chapter 4, Exercise 3

// This solution scans the string character by character to extract words.
// We cannot conveniently use a StringTokenizer object or the indexOf() method
// in the String class because a word can end with a space or a punctuation character
// such as a period or a comma. For simplicity, we assume a single quote
// is always part of a word.

public class Sort {
  public static void main(String args[]) {
    // Declare the String that is to be sorted:
    String text = "Into the face of the young man who sat on the terrace " +
                  "of the Hotel Magnifique at Cannes crept a look of furtive " +
                  "shame, the shifty, hangdog look which announces that " +
                  "an Englishman is about to talk French." ;

 
    // Determine how many words there are.
    // A word is a sequence of letters that may include a single quote character.
    // Anything else is punctuation or spaces.
    int count = 0;	                     // Counts number of words
    boolean isWord = false;              // Indicates start of a word found
    for (int i = 0 ; i<text.length() ; i++) {
      if(isWord) {                       // If we have found a word...
        if(Character.isLetter(text.charAt(i)) || text.charAt(i) == '\'')
          continue;                      // ...pass over letters or single quote
        else                             // It is not a letter or single quote...                            
          isWord = false;                // so we have come to the end of the word
      }
      else if(Character.isLetter(text.charAt(i))) {
                                         // We have the first letter of a new word
          count++;                       // so increment word count
          isWord = true;                 // and record we have found a word
      }
    }        

    // Create the array of strings to contain all the words:
    String[] words = new String[count];

    // Now extract the words from the text
    int start = 0;                                       // Position of first letter of a word
    int wordIndex = 0;                                   // Current vacant words array element                                   
    isWord = false;                                      // Indicates when a word start is found
    for (int i = 0 ; i<text.length() ; i++) {
      if(!isWord) {                                      // If we are not in a word...
        if(Character.isLetter(text.charAt(i))) {         // look for first letter of a word.
          start = i;                                     // Record word start index
          isWord = true;                                 // We have a word
        }
      }
      else {                                             // We are in a word 
        if(Character.isLetter(text.charAt(i)) || text.charAt(i) == '\'')
          continue;                                      // Still the same word so continue
        else {                                           // It is the end of the word
          isWord = false;                                // so reset word indicator
          words[wordIndex++] = text.substring(start,i);  // and extract the word
        }
      }          
    }
    // If the text ends with a letter, we will not have stored the last word
    if(wordIndex < words.length)
      words[wordIndex] = text.substring(start);

    // Sort the array of words
    String temp = null;                          // Stores a word reference
    boolean exchange = true;                     // Indicate we exchanged a pair of words
    while(exchange) {
      exchange = false;                          // No exchange so far
      for(int i = 1 ; i<words.length ; i++) {    // For each word starting with the second
      	if(words[i-1].compareTo(words[i])>0) {   // If the previous word is greater
      		temp = words[i];                     // exchange them
      		words[i] = words[i-1];
      		words[i-1] = temp;
      		exchange = true;                     // and record that exchange occurred
      	}
      }
    }

    // Display the sorted array of words:
    for(int j = 0 ; j<words.length ; j++)
      System.out.println(words[j]);
  }
}